21537910564 has 9 divisors (see below), whose sum is σ = 37691857147. Its totient is φ = 10768808524.

The previous prime is 21537910549. The next prime is 21537910591. The reversal of 21537910564 is 46501973512.

The square root of 21537910564 is 146758.

It is a perfect power (a square), and thus also a powerful number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21537910564.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 256827 + ... + 330205.

Almost surely, 2^21537910564 is an apocalyptic number.

21537910564 is the 146758-th square number.

It is an amenable number.

21537910564 is a deficient number, since it is larger than the sum of its proper divisors (16153946583).

21537910564 is an frugal number, since it uses more digits than its factorization.

21537910564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146762 (or 73381 counting only the distinct ones).

The product of its (nonzero) digits is 226800, while the sum is 43.

The spelling of 21537910564 in words is "twenty-one billion, five hundred thirty-seven million, nine hundred ten thousand, five hundred sixty-four".