12 (number)
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|---|---|---|---|---|
| Cardinal | twelve | |||
| Ordinal | 12th (twelfth) |
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| Numeral system | duodecimal | |||
| Factorization | 22× 3 | |||
| Divisors | 1, 2, 3, 4, 6, 12 | |||
| Roman numeral | XII | |||
| Greek prefix | dodeca- | |||
| Latin prefix | duodeca- | |||
| Binary | 11002 | |||
| Ternary | 1103 | |||
| Quaternary | 304 | |||
| Quinary | 225 | |||
| Senary | 206 | |||
| Octal | 148 | |||
| Duodecimal | 1012 | |||
| Hexadecimal | C16 | |||
| Vigesimal | C20 | |||
| Base 36 | C36 | |||
| Mathematical properties | |
| φ(12) = 4 | τ(12) = 6 |
| σ(12) = 28 | π(12) = 5 |
| μ(12) = 0 | M(12) = -2 |
12 (twelve 
i/ˈtwɛlv/) is the natural number following 11 and preceding 13. The product of the first three factorials, twelve is a superior highly composite number, divisible by 2, 3, 4, and 6. It is central to many systems of counting, including the Western calendar and units of time, and frequently appears in the Abrahamic religions.
The word "twelve" is the largest number with a single-syllable name in English. Early Germanic numbers have been theorized to have been non-decimal: evidence includes the unusual phrasing of eleven and twelve, the former use of "hundred" to refer to groups of 120, and the presence of glosses such as "tentywise" or "ten-count" in medieval texts showing that writers could not presume their readers would normally understand them that way. Such uses gradually disappeared with the introduction of Arabic numerals during the 12th-century Renaissance.
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