21565230 has 16 divisors (see below), whose sum is σ = 51756624. Its totient is φ = 5750720.

The previous prime is 21565199. The next prime is 21565261. The reversal of 21565230 is 3256512.

It is an interprime number because it is at equal distance from previous prime (21565199) and next prime (21565261).

It is a self number, because there is not a number n which added to its sum of digits gives 21565230.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 359391 + ... + 359450.

It is an arithmetic number, because the mean of its divisors is an integer number (3234789).

Almost surely, 2^21565230 is an apocalyptic number.

21565230 is an abundant number, since it is smaller than the sum of its proper divisors (30191394).

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

21565230 is a wasteful number, since it uses less digits than its factorization.

21565230 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 718851.

The product of its (nonzero) digits is 1800, while the sum is 24.

The square root of 21565230 is about 4643.8378524664. The cubic root of 21565230 is about 278.3458163891.

The spelling of 21565230 in words is "twenty-one million, five hundred sixty-five thousand, two hundred thirty".