31686 has 8 divisors (see below), whose sum is σ = 63384. Its totient is φ = 10560.

The previous prime is 31667. The next prime is 31687. The reversal of 31686 is 68613.

It is a sphenic number, since it is the product of 3 distinct primes.

31686 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31687) 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, 2635 + ... + 2646.

It is an arithmetic number, because the mean of its divisors is an integer number (7923).

2³¹⁶⁸⁶ is an apocalyptic number.

31686 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31692).

31686 is a wasteful number, since it uses less digits than its factorization.

31686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5286.

The product of its digits is 864, while the sum is 24.

The square root of 31686 is about 178.0056178889. The cubic root of 31686 is about 31.6438370386.

It can be divided in two parts, 31 and 686, that added together give a palindrome (717).

The spelling of 31686 in words is "thirty-one thousand, six hundred eighty-six".