398315917 has 2 divisors, whose sum is σ = 398315918. Its totient is φ = 398315916.

The previous prime is 398315881. The next prime is 398315927. The reversal of 398315917 is 719513893.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 292102281 + 106213636 = 17091^2 + 10306^2 .

It is a cyclic number.

It is not a de Polignac number, because 398315917 - 2⁷ = 398315789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (398315927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199157958 + 199157959.

It is an arithmetic number, because the mean of its divisors is an integer number (199157959).

Almost surely, 2^398315917 is an apocalyptic number.

It is an amenable number.

398315917 is a deficient number, since it is larger than the sum of its proper divisors (1).

398315917 is an equidigital number, since it uses as much as digits as its factorization.

398315917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 204120, while the sum is 46.

The square root of 398315917 is about 19957.8535168489. The cubic root of 398315917 is about 735.7708093527.

It can be divided in two parts, 3983 and 15917, that added together give a triangular number (19900 = T₁₉₉).

The spelling of 398315917 in words is "three hundred ninety-eight million, three hundred fifteen thousand, nine hundred seventeen".