31999013 has 2 divisors, whose sum is σ = 31999014. Its totient is φ = 31999012.

The previous prime is 31999007. The next prime is 31999027. The reversal of 31999013 is 31099913.

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., 31730689 + 268324 = 5633^2 + 518^2 .

It is a cyclic number.

It is not a de Polignac number, because 31999013 - 2⁶ = 31998949 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31699013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15999506 + 15999507.

It is an arithmetic number, because the mean of its divisors is an integer number (15999507).

Almost surely, 2^31999013 is an apocalyptic number.

It is an amenable number.

31999013 is a deficient number, since it is larger than the sum of its proper divisors (1).

31999013 is an equidigital number, since it uses as much as digits as its factorization.

31999013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6561, while the sum is 35.

The square root of 31999013 is about 5656.7670095205. The cubic root of 31999013 is about 317.4769462667.

The spelling of 31999013 in words is "thirty-one million, nine hundred ninety-nine thousand, thirteen".