21051720512 has 28 divisors (see below), whose sum is σ = 41993246976. Its totient is φ = 10470744960.

The previous prime is 21051720499. The next prime is 21051720527. The reversal of 21051720512 is 21502715012.

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, 848858 + ... + 873305.

Almost surely, 2^21051720512 is an apocalyptic number.

It is an amenable number.

21051720512 is a deficient number, since it is larger than the sum of its proper divisors (20941526464).

21051720512 is a wasteful number, since it uses less digits than its factorization.

21051720512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1722366 (or 1722356 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 26.

The spelling of 21051720512 in words is "twenty-one billion, fifty-one million, seven hundred twenty thousand, five hundred twelve".