21655964 has 24 divisors (see below), whose sum is σ = 41463408. Its totient is φ = 9815040.

The previous prime is 21655927. The next prime is 21655973. The reversal of 21655964 is 46955612.

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, 24962 + ... + 25814.

It is an arithmetic number, because the mean of its divisors is an integer number (1727642).

Almost surely, 2^21655964 is an apocalyptic number.

It is an amenable number.

21655964 is a deficient number, since it is larger than the sum of its proper divisors (19807444).

21655964 is a wasteful number, since it uses less digits than its factorization.

21655964 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1445 (or 1443 counting only the distinct ones).

The product of its digits is 64800, while the sum is 38.

The square root of 21655964 is about 4653.5968884294. The cubic root of 21655964 is about 278.7356428488.

The spelling of 21655964 in words is "twenty-one million, six hundred fifty-five thousand, nine hundred sixty-four".