31686613 has 4 divisors (see below), whose sum is σ = 36213280. Its totient is φ = 27159948.

The previous prime is 31686587. The next prime is 31686631. The reversal of 31686613 is 31668613.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 31668613 = 53 ⋅597521.

It is a cyclic number.

It is not a de Polignac number, because 31686613 - 2⁹ = 31686101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31686653) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2263323 + ... + 2263336.

It is an arithmetic number, because the mean of its divisors is an integer number (9053320).

Almost surely, 2^31686613 is an apocalyptic number.

It is an amenable number.

31686613 is a deficient number, since it is larger than the sum of its proper divisors (4526667).

31686613 is an equidigital number, since it uses as much as digits as its factorization.

31686613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4526666.

The product of its digits is 15552, while the sum is 34.

The square root of 31686613 is about 5629.0863379415. The cubic root of 31686613 is about 316.4404109877.

The spelling of 31686613 in words is "thirty-one million, six hundred eighty-six thousand, six hundred thirteen".