15317991 has 36 divisors (see below), whose sum is σ = 24912888. Its totient is φ = 9401184.

The previous prime is 15317989. The next prime is 15318001. The reversal of 15317991 is 19971351.

It is not a de Polignac number, because 15317991 - 2¹ = 15317989 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15317791) 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 in 35 ways as a sum of consecutive naturals, for example, 40881 + ... + 41253.

Almost surely, 2^15317991 is an apocalyptic number.

15317991 is a deficient number, since it is larger than the sum of its proper divisors (9594897).

15317991 is an equidigital number, since it uses as much as digits as its factorization.

15317991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 414 (or 389 counting only the distinct ones).

The product of its digits is 8505, while the sum is 36.

The square root of 15317991 is about 3913.8205119806. The cubic root of 15317991 is about 248.3517759777.

The spelling of 15317991 in words is "fifteen million, three hundred seventeen thousand, nine hundred ninety-one".