21709447256 has 48 divisors (see below), whose sum is σ = 47371343400. Its totient is φ = 9300044544.

The previous prime is 21709447223. The next prime is 21709447261. The reversal of 21709447256 is 65274490712.

It is a super-2 number, since 2×21709447256² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21709447256.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1012115 + ... + 1033341.

Almost surely, 2^21709447256 is an apocalyptic number.

It is an amenable number.

21709447256 is an abundant number, since it is smaller than the sum of its proper divisors (25661896144).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21709447256 is a wasteful number, since it uses less digits than its factorization.

21709447256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23856 (or 23845 counting only the distinct ones).

The product of its (nonzero) digits is 846720, while the sum is 47.

The spelling of 21709447256 in words is "twenty-one billion, seven hundred nine million, four hundred forty-seven thousand, two hundred fifty-six".