31513525021 has 4 divisors (see below), whose sum is σ = 34378390944. Its totient is φ = 28648659100.

The previous prime is 31513524953. The next prime is 31513525027. The reversal of 31513525021 is 12052531513.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 31513525021 - 2¹⁵ = 31513492253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31513525027) 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, 1432432945 + ... + 1432432966.

It is an arithmetic number, because the mean of its divisors is an integer number (8594597736).

Almost surely, 2^31513525021 is an apocalyptic number.

It is an amenable number.

31513525021 is a deficient number, since it is larger than the sum of its proper divisors (2864865923).

31513525021 is a wasteful number, since it uses less digits than its factorization.

31513525021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2864865922.

The product of its (nonzero) digits is 4500, while the sum is 28.

The spelling of 31513525021 in words is "thirty-one billion, five hundred thirteen million, five hundred twenty-five thousand, twenty-one".