21644023536 has 60 divisors (see below), whose sum is σ = 60583231800. Its totient is φ = 7213480320.

The previous prime is 21644023487. The next prime is 21644023561. The reversal of 21644023536 is 63532044612.

21644023536 is a `hidden beast` number, since 2 + 1 + 64 + 40 + 23 + 536 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21644023536.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1480390 + ... + 1494938.

It is an arithmetic number, because the mean of its divisors is an integer number (1009720530).

Almost surely, 2^21644023536 is an apocalyptic number.

It is an amenable number.

21644023536 is an abundant number, since it is smaller than the sum of its proper divisors (38939208264).

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

21644023536 is a wasteful number, since it uses less digits than its factorization.

21644023536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24894 (or 24885 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 36.

The spelling of 21644023536 in words is "twenty-one billion, six hundred forty-four million, twenty-three thousand, five hundred thirty-six".