15975979 has 4 divisors (see below), whose sum is σ = 16816840. Its totient is φ = 15135120.

The previous prime is 15975931. The next prime is 15975991. The reversal of 15975979 is 97957951.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 15975979 - 2⁷ = 15975851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15975079) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 420402 + ... + 420439.

It is an arithmetic number, because the mean of its divisors is an integer number (4204210).

Almost surely, 2^15975979 is an apocalyptic number.

15975979 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

15975979 is a deficient number, since it is larger than the sum of its proper divisors (840861).

15975979 is an equidigital number, since it uses as much as digits as its factorization.

15975979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 840860.

The product of its digits is 893025, while the sum is 52.

The square root of 15975979 is about 3996.9962471836. The cubic root of 15975979 is about 251.8580444719.

The spelling of 15975979 in words is "fifteen million, nine hundred seventy-five thousand, nine hundred seventy-nine".