399191717 has 2 divisors, whose sum is σ = 399191718. Its totient is φ = 399191716.

The previous prime is 399191629. The next prime is 399191731. The reversal of 399191717 is 717191993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 380796196 + 18395521 = 19514^2 + 4289^2 .

It is a cyclic number.

It is not a de Polignac number, because 399191717 - 2⁸ = 399191461 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399191777) 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, 199595858 + 199595859.

It is an arithmetic number, because the mean of its divisors is an integer number (199595859).

Almost surely, 2^399191717 is an apocalyptic number.

It is an amenable number.

399191717 is a deficient number, since it is larger than the sum of its proper divisors (1).

399191717 is an equidigital number, since it uses as much as digits as its factorization.

399191717 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 107163, while the sum is 47.

The square root of 399191717 is about 19979.7827065261. The cubic root of 399191717 is about 736.3096750613.

The spelling of 399191717 in words is "three hundred ninety-nine million, one hundred ninety-one thousand, seven hundred seventeen".