21631555660 has 96 divisors (see below), whose sum is σ = 55688435712. Its totient is φ = 6945227520.

The previous prime is 21631555577. The next prime is 21631555681. The reversal of 21631555660 is 6655513612.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 98644 + ... + 230203.

It is an arithmetic number, because the mean of its divisors is an integer number (580087872).

Almost surely, 2^21631555660 is an apocalyptic number.

21631555660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21631555660 is an abundant number, since it is smaller than the sum of its proper divisors (34056880052).

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

21631555660 is a wasteful number, since it uses less digits than its factorization.

21631555660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328903 (or 328901 counting only the distinct ones).

The product of its (nonzero) digits is 162000, while the sum is 40.

The spelling of 21631555660 in words is "twenty-one billion, six hundred thirty-one million, five hundred fifty-five thousand, six hundred sixty".