21708787648 has 28 divisors (see below), whose sum is σ = 43392833712. Its totient is φ = 10775160320.

The previous prime is 21708787621. The next prime is 21708787673. The reversal of 21708787648 is 84678780712.

It is a super-2 number, since 2×21708787648² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21708787592 and 21708787601.

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, 1229188 + ... + 1246723.

Almost surely, 2^21708787648 is an apocalyptic number.

It is an amenable number.

21708787648 is a deficient number, since it is larger than the sum of its proper divisors (21684046064).

21708787648 is a wasteful number, since it uses less digits than its factorization.

21708787648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2476060 (or 2476050 counting only the distinct ones).

The product of its (nonzero) digits is 8429568, while the sum is 58.

The spelling of 21708787648 in words is "twenty-one billion, seven hundred eight million, seven hundred eighty-seven thousand, six hundred forty-eight".