21664215272 has 32 divisors (see below), whose sum is σ = 46428237120. Its totient is φ = 9283680000.

The previous prime is 21664215271. The next prime is 21664215277. The reversal of 21664215272 is 27251246612.

It is not an unprimeable number, because it can be changed into a prime (21664215271) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 812147 + ... + 838397.

It is an arithmetic number, because the mean of its divisors is an integer number (1450882410).

Almost surely, 2^21664215272 is an apocalyptic number.

It is an amenable number.

21664215272 is an abundant number, since it is smaller than the sum of its proper divisors (24764021848).

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

21664215272 is a wasteful number, since it uses less digits than its factorization.

21664215272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41001 (or 40997 counting only the distinct ones).

The product of its digits is 80640, while the sum is 38.

The spelling of 21664215272 in words is "twenty-one billion, six hundred sixty-four million, two hundred fifteen thousand, two hundred seventy-two".