31689509 has 2 divisors, whose sum is σ = 31689510. Its totient is φ = 31689508.

The previous prime is 31689499. The next prime is 31689521. The reversal of 31689509 is 90598613.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30360100 + 1329409 = 5510^2 + 1153^2 .

It is a cyclic number.

It is not a de Polignac number, because 31689509 - 2²⁰ = 30640933 is a prime.

It is a super-2 number, since 2×31689509² = 2008449961322162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31689529) 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, 15844754 + 15844755.

It is an arithmetic number, because the mean of its divisors is an integer number (15844755).

Almost surely, 2^31689509 is an apocalyptic number.

It is an amenable number.

31689509 is a deficient number, since it is larger than the sum of its proper divisors (1).

31689509 is an equidigital number, since it uses as much as digits as its factorization.

31689509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 58320, while the sum is 41.

The square root of 31689509 is about 5629.3435674153. The cubic root of 31689509 is about 316.4500510578.

The spelling of 31689509 in words is "thirty-one million, six hundred eighty-nine thousand, five hundred nine".