15997515 has 16 divisors (see below), whose sum is σ = 25762848. Its totient is φ = 8476416.

The previous prime is 15997481. The next prime is 15997517. The reversal of 15997515 is 51579951.

15997515 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 15997515 - 2⁶ = 15997451 is a prime.

It is not an unprimeable number, because it can be changed into a prime (15997517) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1042 + ... + 5751.

It is an arithmetic number, because the mean of its divisors is an integer number (1610178).

Almost surely, 2^15997515 is an apocalyptic number.

15997515 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

15997515 is a deficient number, since it is larger than the sum of its proper divisors (9765333).

15997515 is a wasteful number, since it uses less digits than its factorization.

15997515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6958.

The product of its digits is 70875, while the sum is 42.

The square root of 15997515 is about 3999.6893629381. The cubic root of 15997515 is about 251.9711638710.

The spelling of 15997515 in words is "fifteen million, nine hundred ninety-seven thousand, five hundred fifteen".