21664309308 has 24 divisors (see below), whose sum is σ = 51782984400. Its totient is φ = 7045303680.

The previous prime is 21664309283. The next prime is 21664309313. The reversal of 21664309308 is 80390346612.

It is a self number, because there is not a number n which added to its sum of digits gives 21664309308.

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, 22016083 + ... + 22017066.

It is an arithmetic number, because the mean of its divisors is an integer number (2157624350).

Almost surely, 2^21664309308 is an apocalyptic number.

It is an amenable number.

21664309308 is an abundant number, since it is smaller than the sum of its proper divisors (30118675092).

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

21664309308 is a wasteful number, since it uses less digits than its factorization.

21664309308 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44033197 (or 44033195 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 42.

The spelling of 21664309308 in words is "twenty-one billion, six hundred sixty-four million, three hundred nine thousand, three hundred eight".