21658361868 has 72 divisors (see below), whose sum is σ = 64318786896. Its totient is φ = 6058281600.

The previous prime is 21658361849. The next prime is 21658361869. The reversal of 21658361868 is 86816385612.

21658361868 is a `hidden beast` number, since 2 + 16 + 5 + 8 + 3 + 618 + 6 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (21658361869) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2098423 + ... + 2108718.

Almost surely, 2^21658361868 is an apocalyptic number.

It is an amenable number.

21658361868 is an abundant number, since it is smaller than the sum of its proper divisors (42660425028).

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

21658361868 is a wasteful number, since it uses less digits than its factorization.

21658361868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4207175 (or 4207170 counting only the distinct ones).

The product of its digits is 3317760, while the sum is 54.

The spelling of 21658361868 in words is "twenty-one billion, six hundred fifty-eight million, three hundred sixty-one thousand, eight hundred sixty-eight".