31688113 has 2 divisors, whose sum is σ = 31688114. Its totient is φ = 31688112.

The previous prime is 31688071. The next prime is 31688123. The reversal of 31688113 is 31188613.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28217344 + 3470769 = 5312^2 + 1863^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31688113 is a prime.

It is equal to p_1955740 and since 31688113 and 1955740 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (31688123) 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, 15844056 + 15844057.

It is an arithmetic number, because the mean of its divisors is an integer number (15844057).

Almost surely, 2^31688113 is an apocalyptic number.

It is an amenable number.

31688113 is a deficient number, since it is larger than the sum of its proper divisors (1).

31688113 is an equidigital number, since it uses as much as digits as its factorization.

31688113 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 31.

The square root of 31688113 is about 5629.2195729071. The cubic root of 31688113 is about 316.4454041912.

Subtracting from 31688113 its reverse (31188613), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 31688113 in words is "thirty-one million, six hundred eighty-eight thousand, one hundred thirteen".