21664080840 has 32 divisors (see below), whose sum is σ = 64992242880. Its totient is φ = 5777088192.

The previous prime is 21664080803. The next prime is 21664080869. The reversal of 21664080840 is 4808046612.

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, 90266884 + ... + 90267123.

It is an arithmetic number, because the mean of its divisors is an integer number (2031007590).

Almost surely, 2^21664080840 is an apocalyptic number.

21664080840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21664080840 is an abundant number, since it is smaller than the sum of its proper divisors (43328162040).

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

21664080840 is a wasteful number, since it uses less digits than its factorization.

21664080840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180534021 (or 180534017 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 39.

The spelling of 21664080840 in words is "twenty-one billion, six hundred sixty-four million, eighty thousand, eight hundred forty".