15721428715 has 4 divisors (see below), whose sum is σ = 18865714464. Its totient is φ = 12577142968.

The previous prime is 15721428707. The next prime is 15721428739. The reversal of 15721428715 is 51782412751.

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 15721428715 - 2³ = 15721428707 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1572142867 + ... + 1572142876.

It is an arithmetic number, because the mean of its divisors is an integer number (4716428616).

Almost surely, 2^15721428715 is an apocalyptic number.

15721428715 is a deficient number, since it is larger than the sum of its proper divisors (3144285749).

15721428715 is an equidigital number, since it uses as much as digits as its factorization.

15721428715 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3144285748.

The product of its digits is 156800, while the sum is 43.

The spelling of 15721428715 in words is "fifteen billion, seven hundred twenty-one million, four hundred twenty-eight thousand, seven hundred fifteen".