31989861 has 12 divisors (see below), whose sum is σ = 47698560. Its totient is φ = 20638440.

The previous prime is 31989857. The next prime is 31989889. The reversal of 31989861 is 16898913.

It is not a de Polignac number, because 31989861 - 2² = 31989857 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31989851) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 57051 + ... + 57608.

It is an arithmetic number, because the mean of its divisors is an integer number (3974880).

Almost surely, 2^31989861 is an apocalyptic number.

31989861 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

31989861 is a deficient number, since it is larger than the sum of its proper divisors (15708699).

31989861 is a wasteful number, since it uses less digits than its factorization.

31989861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114696 (or 114693 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 31989861 is about 5655.9580090379. The cubic root of 31989861 is about 317.4466763116.

The spelling of 31989861 in words is "thirty-one million, nine hundred eighty-nine thousand, eight hundred sixty-one".