31661685 has 96 divisors (see below), whose sum is σ = 65415168. Its totient is φ = 14541120.

The previous prime is 31661681. The next prime is 31661689. The reversal of 31661685 is 58616613.

It is a happy number.

31661685 is a `hidden beast` number, since 31 + 6 + 616 + 8 + 5 = 666.

It is an interprime number because it is at equal distance from previous prime (31661681) and next prime (31661689).

It is not a de Polignac number, because 31661685 - 2² = 31661681 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31661681) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 307344 + ... + 307446.

It is an arithmetic number, because the mean of its divisors is an integer number (681408).

Almost surely, 2^31661685 is an apocalyptic number.

It is an amenable number.

31661685 is an abundant number, since it is smaller than the sum of its proper divisors (33753483).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31661685 is a wasteful number, since it uses less digits than its factorization.

31661685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157 (or 145 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 31661685 is about 5626.8716886028. The cubic root of 31661685 is about 316.3574075225.

It can be divided in two parts, 3166 and 1685, that added together give a triangular number (4851 = T₉₈).

The spelling of 31661685 in words is "thirty-one million, six hundred sixty-one thousand, six hundred eighty-five".