21512654664 has 16 divisors (see below), whose sum is σ = 53781636720. Its totient is φ = 7170884880.

The previous prime is 21512654621. The next prime is 21512654687. The reversal of 21512654664 is 46645621512.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 448180282 + ... + 448180329.

It is an arithmetic number, because the mean of its divisors is an integer number (3361352295).

Almost surely, 2^21512654664 is an apocalyptic number.

21512654664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21512654664 is an abundant number, since it is smaller than the sum of its proper divisors (32268982056).

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

21512654664 is a wasteful number, since it uses less digits than its factorization.

21512654664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 896360620 (or 896360616 counting only the distinct ones).

The product of its digits is 345600, while the sum is 42.

The spelling of 21512654664 in words is "twenty-one billion, five hundred twelve million, six hundred fifty-four thousand, six hundred sixty-four".