31307993 has 2 divisors, whose sum is σ = 31307994. Its totient is φ = 31307992.

The previous prime is 31307989. The next prime is 31308019. The reversal of 31307993 is 39970313.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29899024 + 1408969 = 5468^2 + 1187^2 .

It is a cyclic number.

It is not a de Polignac number, because 31307993 - 2² = 31307989 is a prime.

It is not a weakly prime, because it can be changed into another prime (31307963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15653996 + 15653997.

It is an arithmetic number, because the mean of its divisors is an integer number (15653997).

Almost surely, 2^31307993 is an apocalyptic number.

It is an amenable number.

31307993 is a deficient number, since it is larger than the sum of its proper divisors (1).

31307993 is an equidigital number, since it uses as much as digits as its factorization.

31307993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15309, while the sum is 35.

The square root of 31307993 is about 5595.3545910871. The cubic root of 31307993 is about 315.1749863392.

The spelling of 31307993 in words is "thirty-one million, three hundred seven thousand, nine hundred ninety-three".