28809 has 16 divisors (see below), whose sum is σ = 47040. Its totient is φ = 17280.

The previous prime is 28807. The next prime is 28813. The reversal of 28809 is 90882.

It is not a de Polignac number, because 28809 - 2¹ = 28807 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 28809.

It is not an unprimeable number, because it can be changed into a prime (28807) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 249 + ... + 345.

It is an arithmetic number, because the mean of its divisors is an integer number (2940).

2²⁸⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

28809 is a deficient number, since it is larger than the sum of its proper divisors (18231).

28809 is a wasteful number, since it uses less digits than its factorization.

With its successor (28810) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (117).

28809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117 (or 111 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 28809 is about 169.7321419178. The cubic root of 28809 is about 30.6555699192.

Subtracting from 28809 its sum of digits (27), we obtain a palindrome (28782).

The spelling of 28809 in words is "twenty-eight thousand, eight hundred nine".