21261037564 has 18 divisors (see below), whose sum is σ = 40289038440. Its totient is φ = 9812786256.

The previous prime is 21261037559. The next prime is 21261037591. The reversal of 21261037564 is 46573016212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 15724944 + ... + 15726295.

Almost surely, 2^21261037564 is an apocalyptic number.

It is an amenable number.

21261037564 is a deficient number, since it is larger than the sum of its proper divisors (19028000876).

21261037564 is a wasteful number, since it uses less digits than its factorization.

21261037564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31451269 (or 31451254 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 37.

The spelling of 21261037564 in words is "twenty-one billion, two hundred sixty-one million, thirty-seven thousand, five hundred sixty-four".