15979857121 has 4 divisors (see below), whose sum is σ = 15989765652. Its totient is φ = 15969948592.

The previous prime is 15979857097. The next prime is 15979857137. The reversal of 15979857121 is 12175897951.

15979857121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3667513600 + 12312343521 = 60560^2 + 110961^2 .

It is a cyclic number.

It is not a de Polignac number, because 15979857121 - 2⁹ = 15979856609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15979857191) 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 3 ways as a sum of consecutive naturals, for example, 4951846 + ... + 4955071.

It is an arithmetic number, because the mean of its divisors is an integer number (3997441413).

Almost surely, 2^15979857121 is an apocalyptic number.

It is an amenable number.

15979857121 is a deficient number, since it is larger than the sum of its proper divisors (9908531).

15979857121 is an equidigital number, since it uses as much as digits as its factorization.

15979857121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9908530.

The product of its digits is 1587600, while the sum is 55.

The spelling of 15979857121 in words is "fifteen billion, nine hundred seventy-nine million, eight hundred fifty-seven thousand, one hundred twenty-one".