31997513 has 2 divisors, whose sum is σ = 31997514. Its totient is φ = 31997512.

The previous prime is 31997477. The next prime is 31997521. The reversal of 31997513 is 31579913.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16418704 + 15578809 = 4052^2 + 3947^2 .

It is an emirp because it is prime and its reverse (31579913) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31997513 - 2¹⁸ = 31735369 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (31997533) 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 as a sum of consecutive naturals, namely, 15998756 + 15998757.

It is an arithmetic number, because the mean of its divisors is an integer number (15998757).

Almost surely, 2^31997513 is an apocalyptic number.

It is an amenable number.

31997513 is a deficient number, since it is larger than the sum of its proper divisors (1).

31997513 is an equidigital number, since it uses as much as digits as its factorization.

31997513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25515, while the sum is 38.

The square root of 31997513 is about 5656.6344234005. The cubic root of 31997513 is about 317.4719854589.

It can be divided in two parts, 31 and 997513, that multiplied together give a palindrome (30922903).

The spelling of 31997513 in words is "thirty-one million, nine hundred ninety-seven thousand, five hundred thirteen".