31557213 has 12 divisors (see below), whose sum is σ = 45699420. Its totient is φ = 20984256.

The previous prime is 31557203. The next prime is 31557217. The reversal of 31557213 is 31275513.

It can be written as a sum of positive squares in 2 ways, for example, as 20548089 + 11009124 = 4533^2 + 3318^2 .

It is not a de Polignac number, because 31557213 - 2⁸ = 31556957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31557217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 606 + ... + 7967.

It is an arithmetic number, because the mean of its divisors is an integer number (3808285).

Almost surely, 2^31557213 is an apocalyptic number.

It is an amenable number.

31557213 is a deficient number, since it is larger than the sum of its proper divisors (14142207).

31557213 is a wasteful number, since it uses less digits than its factorization.

31557213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8988 (or 8985 counting only the distinct ones).

The product of its digits is 3150, while the sum is 27.

The square root of 31557213 is about 5617.5807070304. The cubic root of 31557213 is about 316.0090694668.

The spelling of 31557213 in words is "thirty-one million, five hundred fifty-seven thousand, two hundred thirteen".