21639996564 has 72 divisors (see below), whose sum is σ = 52628643648. Its totient is φ = 6919153920.

The previous prime is 21639996551. The next prime is 21639996569. The reversal of 21639996564 is 46569993612.

It is a junction number, because it is equal to n+sod(n) for n = 21639996498 and 21639996507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21639996569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1157112 + ... + 1175664.

It is an arithmetic number, because the mean of its divisors is an integer number (730953384).

Almost surely, 2^21639996564 is an apocalyptic number.

It is an amenable number.

21639996564 is an abundant number, since it is smaller than the sum of its proper divisors (30988647084).

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

21639996564 is a wasteful number, since it uses less digits than its factorization.

21639996564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18705 (or 18666 counting only the distinct ones).

The product of its digits is 18895680, while the sum is 60.

The spelling of 21639996564 in words is "twenty-one billion, six hundred thirty-nine million, nine hundred ninety-six thousand, five hundred sixty-four".