31997257 has 4 divisors (see below), whose sum is σ = 32474896. Its totient is φ = 31519620.

The previous prime is 31997249. The next prime is 31997299. The reversal of 31997257 is 75279913.

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 31997257 - 2³ = 31997249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31997227) 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 3 ways as a sum of consecutive naturals, for example, 238719 + ... + 238852.

It is an arithmetic number, because the mean of its divisors is an integer number (8118724).

Almost surely, 2^31997257 is an apocalyptic number.

It is an amenable number.

31997257 is a deficient number, since it is larger than the sum of its proper divisors (477639).

31997257 is an equidigital number, since it uses as much as digits as its factorization.

31997257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 477638.

The product of its digits is 119070, while the sum is 43.

The square root of 31997257 is about 5656.6117950589. The cubic root of 31997257 is about 317.4711387988.

The spelling of 31997257 in words is "thirty-one million, nine hundred ninety-seven thousand, two hundred fifty-seven".