31345991 has 12 divisors (see below), whose sum is σ = 34161984. Its totient is φ = 28728000.

The previous prime is 31345973. The next prime is 31345997. The reversal of 31345991 is 19954313.

It is not a de Polignac number, because 31345991 - 2⁶ = 31345927 is a prime.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31345997) 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, 9791 + ... + 12591.

It is an arithmetic number, because the mean of its divisors is an integer number (2846832).

Almost surely, 2^31345991 is an apocalyptic number.

31345991 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

31345991 is a deficient number, since it is larger than the sum of its proper divisors (2815993).

31345991 is a wasteful number, since it uses less digits than its factorization.

31345991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2870 (or 2851 counting only the distinct ones).

The product of its digits is 14580, while the sum is 35.

The square root of 31345991 is about 5598.7490567090. The cubic root of 31345991 is about 315.3024423679.

The spelling of 31345991 in words is "thirty-one million, three hundred forty-five thousand, nine hundred ninety-one".