21564164 has 24 divisors (see below), whose sum is σ = 40575360. Its totient is φ = 9995616.

The previous prime is 21564149. The next prime is 21564181. The reversal of 21564164 is 46146512.

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, 554 + ... + 6590.

It is an arithmetic number, because the mean of its divisors is an integer number (1690640).

Almost surely, 2^21564164 is an apocalyptic number.

It is an amenable number.

21564164 is a deficient number, since it is larger than the sum of its proper divisors (19011196).

21564164 is a wasteful number, since it uses less digits than its factorization.

21564164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6107 (or 6105 counting only the distinct ones).

The product of its digits is 5760, while the sum is 29.

The square root of 21564164 is about 4643.7230752921. The cubic root of 21564164 is about 278.3412299703.

The spelling of 21564164 in words is "twenty-one million, five hundred sixty-four thousand, one hundred sixty-four".