21665270660 has 24 divisors (see below), whose sum is σ = 49633166016. Its totient is φ = 7878280160.

The previous prime is 21665270639. The next prime is 21665270677. The reversal of 21665270660 is 6607256612.

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, 49239032 + ... + 49239471.

It is an arithmetic number, because the mean of its divisors is an integer number (2068048584).

Almost surely, 2^21665270660 is an apocalyptic number.

21665270660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21665270660 is an abundant number, since it is smaller than the sum of its proper divisors (27967895356).

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

21665270660 is a wasteful number, since it uses less digits than its factorization.

21665270660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98478523 (or 98478521 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 41.

The spelling of 21665270660 in words is "twenty-one billion, six hundred sixty-five million, two hundred seventy thousand, six hundred sixty".