31557139 has 2 divisors, whose sum is σ = 31557140. Its totient is φ = 31557138.

The previous prime is 31557131. The next prime is 31557161. The reversal of 31557139 is 93175513.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31557139 - 2³ = 31557131 is a prime.

It is not a weakly prime, because it can be changed into another prime (31557131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15778569 + 15778570.

It is an arithmetic number, because the mean of its divisors is an integer number (15778570).

Almost surely, 2^31557139 is an apocalyptic number.

31557139 is a deficient number, since it is larger than the sum of its proper divisors (1).

31557139 is an equidigital number, since it uses as much as digits as its factorization.

31557139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14175, while the sum is 34.

The square root of 31557139 is about 5617.5741205613. The cubic root of 31557139 is about 316.0088224584.

The spelling of 31557139 in words is "thirty-one million, five hundred fifty-seven thousand, one hundred thirty-nine".