21064638 has 32 divisors (see below), whose sum is σ = 49061376. Its totient is φ = 5904288.

The previous prime is 21064627. The next prime is 21064679. The reversal of 21064638 is 83646012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2506 + ... + 6957.

It is an arithmetic number, because the mean of its divisors is an integer number (1533168).

Almost surely, 2^21064638 is an apocalyptic number.

21064638 is an abundant number, since it is smaller than the sum of its proper divisors (27996738).

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

21064638 is a wasteful number, since it uses less digits than its factorization.

21064638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9528.

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 21064638 is about 4589.6228603231. The cubic root of 21064638 is about 276.1751933289.

The spelling of 21064638 in words is "twenty-one million, sixty-four thousand, six hundred thirty-eight".