31986 has 12 divisors (see below), whose sum is σ = 69342. Its totient is φ = 10656.

The previous prime is 31981. The next prime is 31991. The reversal of 31986 is 68913.

It is an interprime number because it is at equal distance from previous prime (31981) and next prime (31991).

It can be written as a sum of positive squares in only one way, i.e., 27225 + 4761 = 165^2 + 69^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31981) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 871 + ... + 906.

2³¹⁹⁸⁶ is an apocalyptic number.

31986 is an abundant number, since it is smaller than the sum of its proper divisors (37356).

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

31986 is a wasteful number, since it uses less digits than its factorization.

31986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1785 (or 1782 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 31986 is about 178.8463027295. The cubic root of 31986 is about 31.7433904443.

The spelling of 31986 in words is "thirty-one thousand, nine hundred eighty-six".