21255231521316 has 96 divisors (see below), whose sum is σ = 56609918039808. Its totient is φ = 6149098598400.

The previous prime is 21255231521257. The next prime is 21255231521339. The reversal of 21255231521316 is 61312513255212.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1469785 + ... + 6683616.

It is an arithmetic number, because the mean of its divisors is an integer number (589686646248).

Almost surely, 2^{21255231521316} is an apocalyptic number.

21255231521316 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21255231521316 is an abundant number, since it is smaller than the sum of its proper divisors (35354686518492).

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

21255231521316 is a wasteful number, since it uses less digits than its factorization.

21255231521316 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8154421 (or 8154419 counting only the distinct ones).

The product of its digits is 108000, while the sum is 39.

Adding to 21255231521316 its reverse (61312513255212), we get a palindrome (82567744776528).

The spelling of 21255231521316 in words is "twenty-one trillion, two hundred fifty-five billion, two hundred thirty-one million, five hundred twenty-one thousand, three hundred sixteen".