21351640564 has 12 divisors (see below), whose sum is σ = 39331969600. Its totient is φ = 10113934968.

The previous prime is 21351640559. The next prime is 21351640573. The reversal of 21351640564 is 46504615312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 140471244 + ... + 140471395.

Almost surely, 2^21351640564 is an apocalyptic number.

It is an amenable number.

21351640564 is a deficient number, since it is larger than the sum of its proper divisors (17980329036).

21351640564 is a wasteful number, since it uses less digits than its factorization.

21351640564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280942662 (or 280942660 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 37.

The spelling of 21351640564 in words is "twenty-one billion, three hundred fifty-one million, six hundred forty thousand, five hundred sixty-four".