31991983 has 4 divisors (see below), whose sum is σ = 32534280. Its totient is φ = 31449688.

The previous prime is 31991941. The next prime is 31991989. The reversal of 31991983 is 38919913.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 31991983 - 2⁹ = 31991471 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 (31991989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 271060 + ... + 271177.

It is an arithmetic number, because the mean of its divisors is an integer number (8133570).

Almost surely, 2^31991983 is an apocalyptic number.

31991983 is a deficient number, since it is larger than the sum of its proper divisors (542297).

31991983 is an equidigital number, since it uses as much as digits as its factorization.

31991983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542296.

The product of its digits is 52488, while the sum is 43.

The square root of 31991983 is about 5656.1455957215. The cubic root of 31991983 is about 317.4536952746.

The spelling of 31991983 in words is "thirty-one million, nine hundred ninety-one thousand, nine hundred eighty-three".