31872521 has 4 divisors (see below), whose sum is σ = 31944912. Its totient is φ = 31800132.

The previous prime is 31872517. The next prime is 31872523. The reversal of 31872521 is 12527813.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12527813 = 31 ⋅404123.

It is a cyclic number.

It is not a de Polignac number, because 31872521 - 2² = 31872517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31872523) 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, 35531 + ... + 36416.

It is an arithmetic number, because the mean of its divisors is an integer number (7986228).

Almost surely, 2^31872521 is an apocalyptic number.

It is an amenable number.

31872521 is a deficient number, since it is larger than the sum of its proper divisors (72391).

31872521 is an equidigital number, since it uses as much as digits as its factorization.

31872521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72390.

The product of its digits is 3360, while the sum is 29.

The square root of 31872521 is about 5645.5753471192. The cubic root of 31872521 is about 317.0580653717.

The spelling of 31872521 in words is "thirty-one million, eight hundred seventy-two thousand, five hundred twenty-one".