21879831538944 has 126 divisors (see below), whose sum is σ = 65481338171186. Its totient is φ = 7293277117440.

The previous prime is 21879831538927. The next prime is 21879831538949. The reversal of 21879831538944 is 44983513897812.

21879831538944 is a `hidden beast` number, since 2 + 1 + 8 + 7 + 9 + 83 + 1 + 538 + 9 + 4 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 20708761273344 + 1171070265600 = 4550688^2 + 1082160^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21879831538949) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 58433467 + ... + 58806714.

Almost surely, 2^{21879831538944} is an apocalyptic number.

21879831538944 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21879831538944 is an abundant number, since it is smaller than the sum of its proper divisors (43601506632242).

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

21879831538944 is an frugal number, since it uses more digits than its factorization.

21879831538944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117240215 (or 117240186 counting only the distinct ones).

The product of its digits is 418037760, while the sum is 72.

The spelling of 21879831538944 in words is "twenty-one trillion, eight hundred seventy-nine billion, eight hundred thirty-one million, five hundred thirty-eight thousand, nine hundred forty-four".