21639656862 has 72 divisors (see below), whose sum is σ = 48503748384. Its totient is φ = 6971795712.

The previous prime is 21639656839. The next prime is 21639656887. The reversal of 21639656862 is 26865693612.

21639656862 is a `hidden beast` number, since 2 + 16 + 3 + 9 + 6 + 568 + 62 = 666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21639656799 and 21639656808.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3225003 + ... + 3231705.

It is an arithmetic number, because the mean of its divisors is an integer number (673663172).

Almost surely, 2^21639656862 is an apocalyptic number.

21639656862 is an abundant number, since it is smaller than the sum of its proper divisors (26864091522).

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

21639656862 is a wasteful number, since it uses less digits than its factorization.

21639656862 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6894 (or 6848 counting only the distinct ones).

The product of its digits is 5598720, while the sum is 54.

The spelling of 21639656862 in words is "twenty-one billion, six hundred thirty-nine million, six hundred fifty-six thousand, eight hundred sixty-two".