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

In Mathematics

22 is a semiprime, a Smith number, and an Erdős–Woods number. is a commonly used approximation of the irrational number π, 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. 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. There are also 22 regular complex apeirohedra.

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Twenty-two may also refer to: