21557731344 has 40 divisors (see below), whose sum is σ = 56741582592. Its totient is φ = 7050326400.

The previous prime is 21557731339. The next prime is 21557731357. The reversal of 21557731344 is 44313775512.

It is a junction number, because it is equal to n+sod(n) for n = 21557731296 and 21557731305.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4234432 + ... + 4239519.

Almost surely, 2^21557731344 is an apocalyptic number.

21557731344 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21557731344 is an abundant number, since it is smaller than the sum of its proper divisors (35183851248).

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

21557731344 is a wasteful number, since it uses less digits than its factorization.

21557731344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8474015 (or 8474009 counting only the distinct ones).

The product of its digits is 352800, while the sum is 42.

The spelling of 21557731344 in words is "twenty-one billion, five hundred fifty-seven million, seven hundred thirty-one thousand, three hundred forty-four".