21658115868 has 24 divisors (see below), whose sum is σ = 50544573072. Its totient is φ = 7218090624.

The previous prime is 21658115839. The next prime is 21658115909. The reversal of 21658115868 is 86851185612.

It is a self number, because there is not a number n which added to its sum of digits gives 21658115868.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88455 + ... + 226142.

It is an arithmetic number, because the mean of its divisors is an integer number (2106023878).

Almost surely, 2^21658115868 is an apocalyptic number.

It is an amenable number.

21658115868 is an abundant number, since it is smaller than the sum of its proper divisors (28886457204).

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

21658115868 is a wasteful number, since it uses less digits than its factorization.

21658115868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320341 (or 320339 counting only the distinct ones).

The product of its digits is 921600, while the sum is 51.

The spelling of 21658115868 in words is "twenty-one billion, six hundred fifty-eight million, one hundred fifteen thousand, eight hundred sixty-eight".