31521344521 has 4 divisors (see below), whose sum is σ = 32290157844. Its totient is φ = 30752531200.

The previous prime is 31521344509. The next prime is 31521344531. The reversal of 31521344521 is 12544312513.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12544312513 = 47309 ⋅265157.

It can be written as a sum of positive squares in 2 ways, for example, as 11313300496 + 20208044025 = 106364^2 + 142155^2 .

It is a cyclic number.

It is not a de Polignac number, because 31521344521 - 2²¹ = 31519247369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31521344531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 384406600 + ... + 384406681.

It is an arithmetic number, because the mean of its divisors is an integer number (8072539461).

Almost surely, 2^31521344521 is an apocalyptic number.

It is an amenable number.

31521344521 is a deficient number, since it is larger than the sum of its proper divisors (768813323).

31521344521 is an equidigital number, since it uses as much as digits as its factorization.

31521344521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768813322.

The product of its digits is 14400, while the sum is 31.

The spelling of 31521344521 in words is "thirty-one billion, five hundred twenty-one million, three hundred forty-four thousand, five hundred twenty-one".