31891986 has 48 divisors (see below), whose sum is σ = 79632384. Its totient is φ = 9035712.

The previous prime is 31891943. The next prime is 31891997. The reversal of 31891986 is 68919813.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15006 + ... + 16998.

It is an arithmetic number, because the mean of its divisors is an integer number (1659008).

Almost surely, 2^31891986 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31891986, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39816192).

31891986 is an abundant number, since it is smaller than the sum of its proper divisors (47740398).

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

31891986 is a wasteful number, since it uses less digits than its factorization.

31891986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2135 (or 2132 counting only the distinct ones).

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

The square root of 31891986 is about 5647.2990004072. The cubic root of 31891986 is about 317.1225961873.

The spelling of 31891986 in words is "thirty-one million, eight hundred ninety-one thousand, nine hundred eighty-six".