21921264 has 30 divisors (see below), whose sum is σ = 61349496. Its totient is φ = 7307040.

The previous prime is 21921259. The next prime is 21921281. The reversal of 21921264 is 46212912.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 75972 + ... + 76259.

Almost surely, 2^21921264 is an apocalyptic number.

21921264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21921264 is an abundant number, since it is smaller than the sum of its proper divisors (39428232).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21921264 is a wasteful number, since it uses less digits than its factorization.

21921264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152245 (or 152236 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 21921264 is about 4682.0149508518. The cubic root of 21921264 is about 279.8692586899.

The spelling of 21921264 in words is "twenty-one million, nine hundred twenty-one thousand, two hundred sixty-four".