253 (number)

253 is the natural number following 252 and preceding 254.

In mathematics

253 is:

a semiprime since it is the product of 2 primes.
a brilliant number, meaning that its prime factors have the same amount of digits
the 22nd triangular number.
a star number.
a centered heptagonal number.
a centered nonagonal number.
a Blum integer.
a member of the 13-aliquot tree.