15728670721 has 12 divisors (see below), whose sum is σ = 16015708800. Its totient is φ = 15446678640.

The previous prime is 15728670709. The next prime is 15728670779. The reversal of 15728670721 is 12707682751.

It is not a de Polignac number, because 15728670721 - 2⁵ = 15728670689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15728670791) 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, 2672460 + ... + 2678338.

It is an arithmetic number, because the mean of its divisors is an integer number (1334642400).

Almost surely, 2^15728670721 is an apocalyptic number.

It is an amenable number.

15728670721 is a deficient number, since it is larger than the sum of its proper divisors (287038079).

15728670721 is an frugal number, since it uses more digits than its factorization.

15728670721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6720 (or 6659 counting only the distinct ones).

The product of its (nonzero) digits is 329280, while the sum is 46.

The spelling of 15728670721 in words is "fifteen billion, seven hundred twenty-eight million, six hundred seventy thousand, seven hundred twenty-one".