22 (number)
Template:Infobox number 22 (twenty-two) is the natural number following 21 and preceding 23.
In mathematicsEdit
22 is a semiprime,<ref>Template:Cite OEIS</ref> a Smith number, and an Erdős–Woods number.<ref>Template:Cite OEIS</ref><ref>Template:Cite OEIS</ref> <math>\frac{22}{7} = 3.14{\color{red}28}\ldots</math> is a commonly used approximation of the irrational number [[Pi|Template:Pi]], the ratio of the circumference of a circle to its diameter.
22 can read as "two twos", which is the only fixed point of John Conway's look-and-say function.<ref>Template:Cite OEIS</ref>
The number 22 appears prominently within sporadic groups. The Mathieu group M22 is one of 26 sporadic finite simple groups, defined as the 3-transitive permutation representation on 22 points.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> There are also 22 regular complex apeirohedra.<ref>Template:Citation</ref>
22 has been proven to be a Lychrel number in base 2,<ref>Template:Cite OEIS</ref> since after 4 steps it reaches 10110100, after 8 steps it reaches 1011101000, after 12 steps it reaches 101111010000, and in general after Template:Math steps it reaches a number consisting of 10, followed by Template:Math ones, followed by 01, followed by Template:Math zeros. This number obviously cannot be a palindrome, and none of the other numbers in the sequence are palindromes.
In other fieldsEdit
- Catch-22 (1961), Joseph Heller's novel, and its 1970 film adaptation gave rise to the expression of logic "catch-22".<ref>{{#invoke:citation/CS1|citation
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- 22 equal temperament is a popular microtonal tuning temperament due to its good approximation of harmonic intervals, especially septimal intervals.
In culture and religionEdit
- 22 is a master number in numerology.<ref>Template:Cite book</ref>
- There are 22 colored properties on a traditional Monopoly board.
In weights and measuresEdit
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In other usesEdit
Twenty-two may also refer to:
- In French jargon, "22" is used as a phrase to warn of the coming of the police (typically "{{#invoke:Lang|lang}} !", in English: "5-0! Cops!")
- In Spanish lottery and bingo, 22 is nicknamed Template:Langx after its shape.<ref name="Cuartas">Template:Cite news</ref><ref name="Sanz">{{#invoke:citation/CS1|citation
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See alsoEdit
ReferencesEdit
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External linksEdit
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