21264438 has 16 divisors (see below), whose sum is σ = 45800496. Its totient is φ = 6542880.

The previous prime is 21264427. The next prime is 21264449. The reversal of 21264438 is 83446212.

It is an interprime number because it is at equal distance from previous prime (21264427) and next prime (21264449).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 136233 + ... + 136388.

It is an arithmetic number, because the mean of its divisors is an integer number (2862531).

Almost surely, 2^21264438 is an apocalyptic number.

21264438 is an abundant number, since it is smaller than the sum of its proper divisors (24536058).

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

21264438 is a wasteful number, since it uses less digits than its factorization.

21264438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272639.

The product of its digits is 9216, while the sum is 30.

The square root of 21264438 is about 4611.3379837093. The cubic root of 21264438 is about 277.0456292916.

The spelling of 21264438 in words is "twenty-one million, two hundred sixty-four thousand, four hundred thirty-eight".