21512787256 has 16 divisors (see below), whose sum is σ = 40339643400. Its totient is φ = 10755549024.

The previous prime is 21512787253. The next prime is 21512787287. The reversal of 21512787256 is 65278721512.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512787253) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10135 + ... + 207673.

Almost surely, 2^21512787256 is an apocalyptic number.

It is an amenable number.

21512787256 is a deficient number, since it is larger than the sum of its proper divisors (18826856144).

21512787256 is a wasteful number, since it uses less digits than its factorization.

21512787256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211158 (or 211154 counting only the distinct ones).

The product of its digits is 470400, while the sum is 46.

The spelling of 21512787256 in words is "twenty-one billion, five hundred twelve million, seven hundred eighty-seven thousand, two hundred fifty-six".