21317408825 has 24 divisors (see below), whose sum is σ = 28108756728. Its totient is φ = 15981793280.

The previous prime is 21317408813. The next prime is 21317408857. The reversal of 21317408825 is 52880471312.

It can be written as a sum of positive squares in 12 ways, for example, as 12643653136 + 8673755689 = 112444^2 + 93133^2 .

It is not a de Polignac number, because 21317408825 - 2¹⁰ = 21317407801 is a prime.

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8612 + ... + 206661.

It is an arithmetic number, because the mean of its divisors is an integer number (1171198197).

Almost surely, 2^21317408825 is an apocalyptic number.

21317408825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21317408825 is a deficient number, since it is larger than the sum of its proper divisors (6791347903).

21317408825 is a wasteful number, since it uses less digits than its factorization.

21317408825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215533 (or 215528 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 41.

The spelling of 21317408825 in words is "twenty-one billion, three hundred seventeen million, four hundred eight thousand, eight hundred twenty-five".