**22** (**twenty-two**) is the natural number following 21 and preceding 23.

- 22 is a deficient number.
^{[1]} - 22 is an even composite number and a semiprime;
^{[2]}its proper divisors are 1, 2, and 11. - 22 is a pentagonal number
^{[3]}and a centered heptagonal number.^{[4]} - When cutting a circle with just six line segments, the maximum number of pieces that can be so created is 22,
^{[5]}thus 22 is a central polygonal number (see lazy caterer's sequence).^{[6]} - 22 is the number of partitions of 8.
- 22 is the sum of the totient function for the first eight integers.
^{[7]} - 22 is a Perrin number, preceded in the sequence by 10, 12, and 17.
^{[8]} - 22 divided by 7 approximates the irrational number π, the ratio of the circumference of a circle to its diameter.
- 22 is an Erdős–Woods number, since it is possible to find sequences of 22 consecutive integers such that each inner member shares a factor with either the first or the last member.
^{[9]} - 22 is a Smith number in base 10.
^{[10]} - "2-2" is the only fixed point of John Conway's look-and-say function.
^{[11]}^{[importance?]}

- 22 is the atomic number of titanium.

- 22 is the designation of the USAF stealth fighter, the F-22 Raptor.

- "Twenty Two" is a song by:
- Karma to Burn 2007
^{[12]} - The Vicar (2013)
^{[13]} - Jordan Sweeney (2008)
^{[14]} - The Good Life (2000)
^{[15]} - Sweet Nectar (1996)
^{[16]} - American Generals (2004)
^{[17]} - Dan Anderson (2007)
^{[18]} - Bad Cash Quartet (2006)
^{[19]} - Millencolin (1999)
^{[20]} - Enter the Worship Circle (2005)
^{[21]} - Blank Dogs (2008)
^{[22]} - Al Candello (2002)
^{[23]} - Amen Dunes (2018)
^{[24]}

- Karma to Burn 2007
- In Jay-Z's song "22 Two's", he rhymes the words: too, to, and two, 22 times in the first verse.
^{[25]} - "22 Acacia Avenue" is a song by Iron Maiden on the album
*The Number of the Beast*^{[26]} *Catch 22*is an album by death metal band Hypocrisy^{[27]}- "22" is a song by Lily Allen on the album
*It's Not Me, It's You*. *22 Dreams*is a song and album by Paul Weller. The album contains 22 songs on it.^{[28]}- The Norwegian electronica project Ugress uses 22 as a recurring theme. All four albums feature a track with 22 in the title.
^{[29]}^{[30]}^{[31]} - "
**Twenty-two**may also refer to:- 22 is the number of the French department Côtes-d'Armor
- "22" is a common name for the .22 calibre .22 Long Rifle cartridge.
- In French jargon, "22" is used as a phrase to warn of the coming of the police (typically
*"22, v'là les flics !"*(In English: "5-0! Cops!") - In photography, f/22 is the largest f-stop (and thus smallest aperture) available on most lenses made for single-lens reflex cameras
- The total number of cases on
*Deal or No Deal* - In Spanish lottery and bingo, 22 is nicknamed
*los dos patitos*, 'the two little ducks' after its shape.^{[42]}^{[43]}

## See also

- Catch 22 (other)
- List of highways numbered 22
- Synchronicity
^{[relevant? – discuss]}

## References

**^**Weisstein, Eric W. "Deficient Number".*mathworld.wolfram.com*. Retrieved 2020-08-12.**^**Weisstein, Eric W. "Semiprime".*mathworld.wolfram.com*. Retrieved 2020-08-12.**^**Sloane, N. J. A. (ed.). "Sequence A000326 (Pentagonal numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-31.**^**Sloane, N. J. A. (ed.). "Sequence A069099 (Centered heptagonal numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-31.**^**Wells, D.*The Penguin Dictionary of Curious and Interesting Numbers*London: Penguin Group. (1986): 31**^**Sloane, N. J. A. (ed.). "Sequence A000124 (Central polygonal numbers (the Lazy Caterer's sequence))".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-31.**^**Sloane, N. J. A. (ed.). "Sequence A002088 (Sum of totient function)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-31.**^**Sloane, N. J. A. (ed.). "Sequence A001608 (Perrin sequence)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-31.**^**Sloane, N. J. A. (ed.). "Sequence A059756 (Erdős-Woods numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-31.**^**Sloane, N. J. A. (ed.). "Sequence A006753 (Smith numbers)".*The On-Line Encyclopedia of Integer Sequences*. OEIS Foundation. Retrieved 2016-05-31.**^**Martin, Oscar (2006). "Look-and-Say Biochemistry: Exponential RNA and Multistranded DNA" (PDF).*American Mathematical Monthly*. Mathematical association of America.**113**(4): 289–307. doi:10.2307/27641915. ISSN 0002-9890. JSTOR 27641915. Archived from the original (PDF) on 2006-12-24. Retrieved 2018-11-21.**^***Twenty Two - Karma to Burn | Song Info | AllMusic*, retrieved 2020-08-12**^***Twenty Two - The Vicar | Song Info | AllMusic*, retrieved 2020-08-12**^***Twenty Two - Jordan Sweeney | Song Info | AllMusic*, retrieved 2020-08-12