21264408 has 48 divisors (see below), whose sum is σ = 62829000. Its totient is φ = 6443520.

The previous prime is 21264391. The next prime is 21264413. The reversal of 21264408 is 80446212.

21264408 is a `hidden beast` number, since 2 + 12 + 644 + 0 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12633 + ... + 14216.

Almost surely, 2^21264408 is an apocalyptic number.

It is an amenable number.

21264408 is an abundant number, since it is smaller than the sum of its proper divisors (41564592).

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

21264408 is a wasteful number, since it uses less digits than its factorization.

21264408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26872 (or 26865 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 21264408 is about 4611.3347308561. The cubic root of 21264408 is about 277.0454990056.

It can be divided in two parts, 212 and 64408, that added together give a triangular number (64620 = T₃₅₉).

The spelling of 21264408 in words is "twenty-one million, two hundred sixty-four thousand, four hundred eight".