31312591 has 4 divisors (see below), whose sum is σ = 32674032. Its totient is φ = 29951152.

The previous prime is 31312579. The next prime is 31312597. The reversal of 31312591 is 19521313.

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

It is a de Polignac number, because none of the positive numbers 2^k-31312591 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 (31312597) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 680686 + ... + 680731.

It is an arithmetic number, because the mean of its divisors is an integer number (8168508).

Almost surely, 2^31312591 is an apocalyptic number.

31312591 is a deficient number, since it is larger than the sum of its proper divisors (1361441).

31312591 is a wasteful number, since it uses less digits than its factorization.

31312591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1361440.

The product of its digits is 810, while the sum is 25.

The square root of 31312591 is about 5595.7654525543. The cubic root of 31312591 is about 315.1904148130.

The spelling of 31312591 in words is "thirty-one million, three hundred twelve thousand, five hundred ninety-one".