twenty-one

　 　 　

WordNet

1. being one more than twenty (同)21, xxi
2. the cardinal number that is the sum of twenty and one (同)21, XXI
3. used informally as an intensifier; "that is one fine dog"
4. the smallest whole number or a numeral representing this number; "he has the one but will need a two and three to go with it"; "they had lunch at one" (同)1, I, ace, single, unity
5. a single person or thing; "he is the best one"; "this is the one I ordered"
6. used of a single unit or thing; not two or more; "`ane is Scottish" (同)1, i, ane
7. having the indivisible character of a unit; "a unitary action"; "spoke with one voice" (同)unitary
8. being a single entity made by combining separate components; "three chemicals combining into one solution"
9. indefinite in time or position; "he will come one day"; "one place or another"
10. of the same kind or quality; "two animals of one species"
11. indicates continuity or persistence or concentration; "his spirit lives on"; "shall I read on?"
12. (of events) planned or scheduled; "the picnic is on, rain or shine"; "we have nothing on for Friday night"
13. in a state required for something to function or be effective; "turn the lights on"; "get a load on"
14. in operation or operational; "left the oven on"; "the switch is in the on position"
15. denoting a quantity consisting of 20 items or units (同)20, xx
16. the cardinal number that is the sum of nineteen and one (同)20, XX

PrepTutorEJDIC

1. 〈C〉〈U〉21 / 《米》(またblackjack)〈U〉(カードゲームの)21(《英》pontoon)
2. 『1個の』,一人の,単一の;《補語にのみ用いて》1歳の / 《時を表す名詞と共に》『ある』… / 《人名に付けて》…という[名の]人 / 同一の,同じ(the same) / 《theまたは所有格を付けて》たった一つの,唯一の / 《another, [the]otherと対比して》一方の / 〈U〉〈C〉『1つ』,1個,一人,1時,1歳 / 〈C〉(数字の)『1』;1の記号(1,Iなど) / 《the O-》超人的なもの / 〈U〉《しばしばa ~》(攻撃・冗談・うそなどの)一発 / 《前に述べた可算名詞を受けて》『それ』 / 《修飾語を伴わないで》 / 《修飾語句を伴って》 / 《後》に「of+複数名詞・代名詞」を伴ってその名詞・代名詞の》『一つ』,一人 / 《後にanother, [the]otherと対照して》一つ,一方 / 《修飾語句を伴って》(特定の)『人』,者 / 《総称的に》『人』 / 私,自分
3. (また《文》upon)《位置・場所》…『の上に』,の上で,の上の / (また《文》upon)《運動・動作の方向・対象》…『に』[向かって] / 《話》…を身につけて / (また《文》upon)《近接して場所》…の近くに,…に面して,…の側に / 《特定の日時》…『に』 / 《状態》…『して』,…中で,…すると / (また《文》upon)…『について』,…に関して / 《目的》…『で』,…に / (また《文》upon)…に基づいて,…によって,…の支え(助け)で / 《所属を表して》(委員会・チームなどの)一員で / (また《文》upon)…を軸にして,…で / (また《文》upon)《前後に同じ名詞を並べて》…に加えて,…についで / 『上に』,『身につけて』 / (電気・水道・ガス・ラジオなどが)『ついて』,通じて / 行われて,続けて,従事して / 《時の副詞[句]を伴って》前方へ,ずっと
4. 〈C〉(数の)『20』;20の記号・〈U〉(24時間制の)20時,20分;20歳 / 〈U〉《補数扱い》『20人,20個』 / 〈C〉20(20人,20個)一組のもの / 《the twenties》(世紀の)20年代;《one's twenties》(年齢の)20代 / 20の,20人の,20個の / 《補語にのみ用いて》20歳の(で)

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/04/02 20:53:43」(JST)

wiki en

[Wiki en表示]

For other uses, see 21 (disambiguation).

← 20 21 22 →
← 20 21 22 23 24 25 26 27 28 29 → List of numbers — Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	twenty-one
Ordinal	21st (twenty-first)
Factorization	3 · 7
Divisors	1, 3, 7, 21
Roman numeral	XXI
Binary	101012
Ternary	2103
Quaternary	1114
Quinary	415
Senary	336
Octal	258
Duodecimal	1912
Hexadecimal	1516
Vigesimal	1120
Base 36	L36

21 (twenty-one) is the natural number following 20 and preceding 22.

In mathematics

Twenty-one is the fifth discrete Semiprime and the second in the (3.q) family. With 22 it forms the second discrete Semiprime pair. As it is a semiprime with both its prime factors being Gaussian primes, 21 is then a Blum integer.

Twenty-one is a Fibonacci number, a Harshad number, a Motzkin number, a triangular number and an octagonal number, as well as a composite number, its proper divisors being 1, 3 and 7.

21 is the sum of the first six natural numbers (1+2+3+4+5+6=21), making it a triangular number.

21 has an aliquot sum of 11 though it is the second composite number found in the 11-aliquot tree with the abundant square prime 18 being the first such member. Twenty-one is the first number to be the aliquot sum of three numbers 18, 51, 91.

21 appears in the Padovan sequence, preceded by the terms 9, 12, 16 (it is the sum of the first two of these).

The sum of divisors for the integers 1 through 6 is 21.

21 is the smallest non-trivial example of a Fibonacci number whose digits are Fibonacci numbers and whose digit sum is also a Fibonacci number.

21 is a repdigit in base 4 (111₄).

21 is the smallest natural number that is not close to a power of 2, 2ⁿ, where the range of closeness is ±n.

21 is the smallest number of differently sized squares needed to square the square.

In science

• The atomic number of scandium

Age 21

In several countries 21 is the age of majority. See also: Coming of age.

In most US states 21 is the drinking age.

In some countries it is the voting age.

In the United States, 21 is the age at which one can purchase multiple tickets to an R-rated film. It is also the age to accompany one under the age of 17 as their parent or adult guardian for an R-rated movie.

In sports

• The jersey number 21 has been retired by several North American sports teams in honor of past playing greats or other key figures:
  • In Major League Baseball:
    • The Cleveland Indians, for Hall of Famer Bob Lemon.
    • The Milwaukee Braves, for Hall of Famer Warren Spahn; the number continues to be honored by the team in its current home of Atlanta.
    • The Pittsburgh Pirates, for Hall of Famer Roberto Clemente, following his death in a plane crash while attempting to deliver humanitarian aid to victims of an earthquake in Nicaragua.
  • In the NBA:
    • The Atlanta Hawks, for Hall of Famer Dominique Wilkins.
    • The Boston Celtics, for Hall of Famer Bill Sharman.
    • The Detroit Pistons, for Hall of Famer Dave Bing.
    • The Sacramento Kings, for Vlade Divac.
    • The Minnesota Timberwolves have not retired the number, but have not issued it since Kevin Garnett was traded from the team in 2007.
  • In the NHL:
    • The Chicago Blackhawks, for Hall of Famer Stan Mikita.
    • The Colorado Avalanche, for Peter Forsberg.
    • The Pittsburgh Penguins, for Michel Brière.
• The number 21 is currently honoured by the Toronto Maple Leafs for Hall of Famer Börje Salming.
  • No NFL team has retired the number.
• In basketball:
  • 21 is a variation of street basketball, in which each player, of which there can be any number, plays for himself only (i.e. not part of a team); the name comes from the requisite number of baskets.
  • In 3x3, a formalized version of three-on-three half-court basketball, the game ends by rule once either team has scored 21 points in regulation.
• In badminton, and table tennis (before 2001), 21 points are required to win a game.
• In the NASCAR Sprint Cup Series the number 21 has long been the car number for Wood Brothers Racing

In other fields

Building called "21" in Zlín, Czech Republic.

Detail of the building entrance

21 is:

• The current century—spanning the years from 2001 to 2100—is referred to as the 21st century. See also: Century 21 (disambiguation).
• The Twenty-first Amendment repealed the Eighteenth Amendment, thereby ending Prohibition.
• Illinois is the 21st state to join the United States.
• The number of spots on a standard cubical (six-sided) die (1+2+3+4+5+6)
• The number of firings in a 21-gun salute honoring Royalty or leaders of countries
• There are 21 trump cards of the tarot deck if one does not consider The Fool to be a proper trump card.
• The standard TCP/IP port number for FTP connection
• The Twenty-One Demands were a set of demands which were sent to the Chinese government by the Japanese government of Okuma Shigenobu in 1915
• 21 Demands of MKS led to the foundation of Solidarity in Poland.
• In Israel, the number is associated with the profile 21 (the military profile designation granting an exemption from the military service)
• 21 grams is the weight of the soul, according to research by Duncan MacDougall, generally regarded as meaningless.
• 21 is the designation of a US Highway connecting Wytheville, Virginia and Beaufort, South Carolina, a truncation of a route that once connected Cleveland, Ohio and Jacksonville, Florida, among other highways past and present.
• The number of the French department Côte-d'Or
• The key value and highest-winning point total of the popular casino game Blackjack.

References

UpToDate Contents

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• 1. 増殖性ループス腎炎における免疫抑制療法の臨床試験 clinical trials of immunosuppressive therapy in proliferative lupus nephritis
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• 5. 透析におけるブラッドアクセスに関連した静脈狭窄に対するステントの使用 use of stents for venous stenosis associated with dialysis vascular access

English Journal

• Ultrasensitive and simultaneous determination of twenty-one amino acids and amines in culture media, red wine and beer.

• Hu Z1, Li L1, Yuan Y1, Yue T2.
• Food chemistry.Food Chem.2014 Sep 1;158:56-65. doi: 10.1016/j.foodchem.2014.02.098. Epub 2014 Feb 28.
• Ultrasensitive and simultaneous determination of amino acids and amines (AAs) in media and winemaking products is very important for evaluating the relationship profile between the depletion of AAs and aroma compounds formation. In this work, by combing the advantages of Taguchi's scheme with Pareto
• PMID 24731314

• Resting-state networks and dissociation in psychogenic non-epileptic seizures.

• van der Kruijs SJ1, Jagannathan SR2, Bodde NM3, Besseling RM4, Lazeron RH3, Vonck KE5, Boon PA6, Cluitmans PJ7, Hofman PA8, Backes WH8, Aldenkamp AP9, Jansen JF10.
• Journal of psychiatric research.J Psychiatr Res.2014 Jul;54:126-33. doi: 10.1016/j.jpsychires.2014.03.010. Epub 2014 Mar 21.
• OBJECTIVE: Psychogenic non-epileptic seizures (PNES) are epilepsy-like episodes which have an emotional rather than organic origin. Although PNES have often been related to the process of dissociation, the psychopathology is still poorly understood. To elucidate underlying mechanisms, the current st
• PMID 24703187

• E-cigarette prevalence and correlates of use among adolescents versus adults: A review and comparison.

• Carroll Chapman SL1, Wu LT2.
• Journal of psychiatric research.J Psychiatr Res.2014 Jul;54C:43-54. doi: 10.1016/j.jpsychires.2014.03.005. Epub 2014 Mar 18.
• Perceived safer than tobacco cigarettes, prevalence of electronic cigarette (e-cigarette) use is increasing. Analyses of cartridges suggest that e-cigarettes may pose health risks. In light of increased use and the potential for consequences, we searched Google Scholar and Pubmed in July of 2013 usi
• PMID 24680203

• Search for peripheral biomarkers in patients affected by acutely psychotic bipolar disorder: a proteomic approach.

• Giusti L1, Mantua V, Da Valle Y, Ciregia F, Ventroni T, Orsolini G, Donadio E, Giannaccini G, Mauri M, Cassano GB, Lucacchini A.
• Molecular bioSystems.Mol Biosyst.2014 Jun 6;10(6):1246-54. doi: 10.1039/c4mb00068d. Epub 2014 Feb 19.
• Data on neurobiological mechanisms underlying mood disorders are elusive; the aetiology of such states is multifactorial, including genetic predisposition and environmental factors. Diagnosis is currently being made only on an interview-based methodology. Biological markers, which could improve the
• PMID 24554194

Japanese Journal

• Immunogenicity and lupus-like autoantibody production can be linked to each other along with type i interferon production in patients with rheumatoid arthritis treated with infliximab: A retrospective study of a single center cohort

• PLOS ONE
• NAID 120005860037

• Conversion to Purkinje-Related Monomorphic Ventricular Tachycardia After Ablation of Ventricular Fibrillation in Ischemic Heart Disease

• Circulation. Arrhythmia and electrophysiology 9(9), e004224, 2016-09
• NAID 120005860195

• Isolation and characterization of twenty-one novel microsatellite loci for the black cicada, Cryptotympana atrata (Hemiptera: Cicadidae)

• Applied entomology and zoology 51(3), 511-514, 2016-08
• NAID 40020901923

• 二十一史通読に見る林鵞峰の学問姿勢 : 『国史館日録』・『南塾乗』との関わりから

• 近世文藝 (104), 43-56, 2016-07
• NAID 40020919615

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「on」「one」

「on」

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「one」

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