15728989 has 4 divisors (see below), whose sum is σ = 15736924. Its totient is φ = 15721056.

The previous prime is 15728939. The next prime is 15729001. The reversal of 15728989 is 98982751.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 98982751 = 7 ⋅14140393.

It can be written as a sum of positive squares in 2 ways, for example, as 5963364 + 9765625 = 2442^2 + 3125^2 .

It is a cyclic number.

It is not a de Polignac number, because 15728989 - 2⁷ = 15728861 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15728929) 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, 1849 + ... + 5905.

It is an arithmetic number, because the mean of its divisors is an integer number (3934231).

Almost surely, 2^15728989 is an apocalyptic number.

It is an amenable number.

15728989 is a deficient number, since it is larger than the sum of its proper divisors (7935).

15728989 is an equidigital number, since it uses as much as digits as its factorization.

15728989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7934.

The product of its digits is 362880, while the sum is 49.

The square root of 15728989 is about 3965.9789459855. The cubic root of 15728989 is about 250.5533821689.

The spelling of 15728989 in words is "fifteen million, seven hundred twenty-eight thousand, nine hundred eighty-nine".