321 is the natural number following 320 and preceding 322.

In mathematics

321 is a semiprime and a member of the Moser-de Bruijn sequence.^[1]

Digits

321's digits are the first 3 natural numbers (excluding 0) in reverse order. This also makes it the reverse of 123.

In culture

321 could be turned into "3, 2, 1, go!" or "Ready, set, go!" as a common countdown.

Further reading

• Countdown

References