15997815 has 12 divisors (see below), whose sum is σ = 27729624. Its totient is φ = 8532144.

The previous prime is 15997789. The next prime is 15997819. The reversal of 15997815 is 51879951.

It is not a de Polignac number, because 15997815 - 2⁵ = 15997783 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 355507 = 15997815 / (1 + 5 + 9 + 9 + 7 + 8 + 1 + 5).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15997819) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 177709 + ... + 177798.

It is an arithmetic number, because the mean of its divisors is an integer number (2310802).

Almost surely, 2^15997815 is an apocalyptic number.

15997815 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

15997815 is a deficient number, since it is larger than the sum of its proper divisors (11731809).

15997815 is a wasteful number, since it uses less digits than its factorization.

15997815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355518 (or 355515 counting only the distinct ones).

The product of its digits is 113400, while the sum is 45.

The square root of 15997815 is about 3999.7268656747. The cubic root of 15997815 is about 251.9727389256.

The spelling of 15997815 in words is "fifteen million, nine hundred ninety-seven thousand, eight hundred fifteen".