Twenty-four (24) is the natural number following twenty-three and preceding twenty-five. It is the factorial of 4 and a composite number, its proper divisors being 1, 2, 3, 4, 6, 8 and 12, making it a highly composite number, and its factorization is:

This number is also the sum of a twin prime (11 + 13).

Twenty-four is also

  • The atomic number of chromium.
  • The number of hours in a day.
  • Usually the number of teeth in a human child's mouth.
  • The number of karats in pure gold.
  • The total number of major and minor keys in Western tonal music, not counting enharmonic equivalents. Therefore, for collections of pieces written in each key, the number of pieces in such a collection; e.g., Chopin's ''24 Preludes.
  • The designation of US Interstate 24, a freeway that runs from Tennessee to Illinois.

The Greek alphabet has twenty-four letters in its classical and modern form.


See also: twenty-two, twenty-three, twenty-five, twenty-six, integer, list of numbers.

This article is about the number. For the year AD 24, see 24. For the television series, see 24 (television).