31257139 has 2 divisors, whose sum is σ = 31257140. Its totient is φ = 31257138.

The previous prime is 31257133. The next prime is 31257143. The reversal of 31257139 is 93175213.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31257139 - 2⁹ = 31256627 is a prime.

It is a Chen prime.

It is equal to p_1930792 and since 31257139 and 1930792 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31257139.

It is not a weakly prime, because it can be changed into another prime (31257133) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15628569 + 15628570.

It is an arithmetic number, because the mean of its divisors is an integer number (15628570).

Almost surely, 2^31257139 is an apocalyptic number.

31257139 is a deficient number, since it is larger than the sum of its proper divisors (1).

31257139 is an equidigital number, since it uses as much as digits as its factorization.

31257139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5670, while the sum is 31.

The square root of 31257139 is about 5590.8084388575. The cubic root of 31257139 is about 315.0042461845.

The spelling of 31257139 in words is "thirty-one million, two hundred fifty-seven thousand, one hundred thirty-nine".