31605913 has 2 divisors, whose sum is σ = 31605914. Its totient is φ = 31605912.

The previous prime is 31605877. The next prime is 31605929. The reversal of 31605913 is 31950613.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21790224 + 9815689 = 4668^2 + 3133^2 .

It is an emirp because it is prime and its reverse (31950613) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31605913 - 2⁹ = 31605401 is a prime.

It is not a weakly prime, because it can be changed into another prime (31605953) 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, 15802956 + 15802957.

It is an arithmetic number, because the mean of its divisors is an integer number (15802957).

Almost surely, 2^31605913 is an apocalyptic number.

It is an amenable number.

31605913 is a deficient number, since it is larger than the sum of its proper divisors (1).

31605913 is an equidigital number, since it uses as much as digits as its factorization.

31605913 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2430, while the sum is 28.

The square root of 31605913 is about 5621.9136421685. The cubic root of 31605913 is about 316.1715440161.

The spelling of 31605913 in words is "thirty-one million, six hundred five thousand, nine hundred thirteen".