21638972893824 has 768 divisors, whose sum is σ = 77478781685760. Its totient is φ = 5924018073600.

The previous prime is 21638972893807. The next prime is 21638972893903. The reversal of 21638972893824 is 42839827983612.

21638972893824 is a `hidden beast` number, since 2 + 16 + 389 + 72 + 8 + 93 + 82 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 208998229 + ... + 209101739.

It is an arithmetic number, because the mean of its divisors is an integer number (100883830320).

Almost surely, 2^{21638972893824} is an apocalyptic number.

21638972893824 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21638972893824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38739390842880).

21638972893824 is an abundant number, since it is smaller than the sum of its proper divisors (55839808791936).

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

21638972893824 is a wasteful number, since it uses less digits than its factorization.

21638972893824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103611 (or 103587 counting only the distinct ones).

The product of its digits is 501645312, while the sum is 72.

The spelling of 21638972893824 in words is "twenty-one trillion, six hundred thirty-eight billion, nine hundred seventy-two million, eight hundred ninety-three thousand, eight hundred twenty-four".