31312139 has 4 divisors (see below), whose sum is σ = 32322240. Its totient is φ = 30302040.

The previous prime is 31312123. The next prime is 31312157. The reversal of 31312139 is 93121313.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93121313 = 659 ⋅141307.

It is a cyclic number.

It is not a de Polignac number, because 31312139 - 2⁴ = 31312123 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31312439) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 505004 + ... + 505065.

It is an arithmetic number, because the mean of its divisors is an integer number (8080560).

Almost surely, 2^31312139 is an apocalyptic number.

31312139 is a deficient number, since it is larger than the sum of its proper divisors (1010101).

31312139 is a wasteful number, since it uses less digits than its factorization.

31312139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1010100.

The product of its digits is 486, while the sum is 23.

The square root of 31312139 is about 5595.7250647258. The cubic root of 31312139 is about 315.1888982053.

The spelling of 31312139 in words is "thirty-one million, three hundred twelve thousand, one hundred thirty-nine".