31391617 has 2 divisors, whose sum is σ = 31391618. Its totient is φ = 31391616.

The previous prime is 31391611. The next prime is 31391663. The reversal of 31391617 is 71619313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26378496 + 5013121 = 5136^2 + 2239^2 .

It is a cyclic number.

It is not a de Polignac number, because 31391617 - 2⁷ = 31391489 is a prime.

It is not a weakly prime, because it can be changed into another prime (31391611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15695808 + 15695809.

It is an arithmetic number, because the mean of its divisors is an integer number (15695809).

Almost surely, 2^31391617 is an apocalyptic number.

It is an amenable number.

31391617 is a deficient number, since it is larger than the sum of its proper divisors (1).

31391617 is an equidigital number, since it uses as much as digits as its factorization.

31391617 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3402, while the sum is 31.

The square root of 31391617 is about 5602.8222352668. The cubic root of 31391617 is about 315.4553488431.

The spelling of 31391617 in words is "thirty-one million, three hundred ninety-one thousand, six hundred seventeen".