21865264 has 20 divisors (see below), whose sum is σ = 44856504. Its totient is φ = 10289408.

The previous prime is 21865243. The next prime is 21865279. The reversal of 21865264 is 46256812.

It is a Harshad number since it is a multiple of its sum of digits (34).

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 3 ways as a sum of consecutive naturals, for example, 39922 + ... + 40465.

Almost surely, 2^21865264 is an apocalyptic number.

It is an amenable number.

21865264 is an abundant number, since it is smaller than the sum of its proper divisors (22991240).

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

21865264 is a wasteful number, since it uses less digits than its factorization.

21865264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80412 (or 80406 counting only the distinct ones).

The product of its digits is 23040, while the sum is 34.

The square root of 21865264 is about 4676.0307954503. The cubic root of 21865264 is about 279.6307377231.

The spelling of 21865264 in words is "twenty-one million, eight hundred sixty-five thousand, two hundred sixty-four".