31231139 has 2 divisors, whose sum is σ = 31231140. Its totient is φ = 31231138.

The previous prime is 31231133. The next prime is 31231223. The reversal of 31231139 is 93113213.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31231139 - 2¹² = 31227043 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31231133) 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 as a sum of consecutive naturals, namely, 15615569 + 15615570.

It is an arithmetic number, because the mean of its divisors is an integer number (15615570).

Almost surely, 2^31231139 is an apocalyptic number.

31231139 is a deficient number, since it is larger than the sum of its proper divisors (1).

31231139 is an equidigital number, since it uses as much as digits as its factorization.

31231139 is an odious number, because the sum of its binary digits is odd.

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

The square root of 31231139 is about 5588.4827100028. The cubic root of 31231139 is about 314.9168807315.

The spelling of 31231139 in words is "thirty-one million, two hundred thirty-one thousand, one hundred thirty-nine".