31913993 has 2 divisors, whose sum is σ = 31913994. Its totient is φ = 31913992.

The previous prime is 31913989. The next prime is 31914011. The reversal of 31913993 is 39931913.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28334329 + 3579664 = 5323^2 + 1892^2 .

It is a cyclic number.

It is not a de Polignac number, because 31913993 - 2² = 31913989 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (31913923) 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, 15956996 + 15956997.

It is an arithmetic number, because the mean of its divisors is an integer number (15956997).

Almost surely, 2^31913993 is an apocalyptic number.

It is an amenable number.

31913993 is a deficient number, since it is larger than the sum of its proper divisors (1).

31913993 is an equidigital number, since it uses as much as digits as its factorization.

31913993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19683, while the sum is 38.

The square root of 31913993 is about 5649.2471179795. The cubic root of 31913993 is about 317.1955226829.

The spelling of 31913993 in words is "thirty-one million, nine hundred thirteen thousand, nine hundred ninety-three".