31686749257 has 4 divisors (see below), whose sum is σ = 31691171476. Its totient is φ = 31682327040.

The previous prime is 31686749251. The next prime is 31686749261. The reversal of 31686749257 is 75294768613.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75294768613 = 103 ⋅731017171.

It can be written as a sum of positive squares in 2 ways, for example, as 30842033161 + 844716096 = 175619^2 + 29064^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31686749257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31686749251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2200344 + ... + 2214697.

It is an arithmetic number, because the mean of its divisors is an integer number (7922792869).

Almost surely, 2^31686749257 is an apocalyptic number.

It is an amenable number.

31686749257 is a deficient number, since it is larger than the sum of its proper divisors (4422219).

31686749257 is an equidigital number, since it uses as much as digits as its factorization.

31686749257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4422218.

The product of its digits is 15240960, while the sum is 58.

The spelling of 31686749257 in words is "thirty-one billion, six hundred eighty-six million, seven hundred forty-nine thousand, two hundred fifty-seven".