Number reference
22 explained.
22: twenty-two, composite, repdigit; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- twenty-two
- Classification
- composite
- Factors
- 1, 2, 11, 22
- Prime factorization
- 2 × 11
- Square root
- 4.690416
- Cube root
- 2.802039
- Binary
- 10110
- Octal
- 26
- Hexadecimal
- 16
- Roman numeral
- XXII
- Digit sum
- 4
- Digital root
- 4
What makes 22 notable
- Repdigit. 22 is written with a single repeated digit, so it is divisible by the repunit of the same length.
22 in everyday use
Twenty-two players take the pitch in a football match, and a cricket pitch is 22 yards long, one chain in the old surveyor's measure. It is the atomic number of titanium. Joseph Heller's 1961 novel Catch-22 gave English a phrase for a no-win rule. The Hebrew alphabet has 22 letters, the Twenty-second Amendment limits a US president to two terms, and the .22 is the most common small-bore rifle cartridge in the world.
The fraction 22/7 is the classic approximation of pi, accurate to about one part in 2,500; Archimedes proved pi was slightly smaller. Twenty-two is a palindrome, twice the prime 11, and the fourth pentagonal number. It is also the number of ways to write 8 as a sum of positive whole numbers, called the partitions of 8. A pizza cut with six straight lines can have at most 22 pieces.
Nearby numbers
How to read this page
The factor list shows every way 22 splits into equal whole-number groups — 4 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 22 for contexts that do not use decimal.
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