28239 has 4 divisors (see below), whose sum is σ = 37656. Its totient is φ = 18824.

The previous prime is 28229. The next prime is 28277. The reversal of 28239 is 93282.

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 28239 - 2⁷ = 28111 is a prime.

It is a super-2 number, since 2×28239² = 1594882242, which contains 22 as substring.

It is a D-number.

28239 is a lucky number.

It is a nialpdrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28219) 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, 4704 + ... + 4709.

It is an arithmetic number, because the mean of its divisors is an integer number (9414).

2²⁸²³⁹ is an apocalyptic number.

28239 is a deficient number, since it is larger than the sum of its proper divisors (9417).

28239 is an equidigital number, since it uses as much as digits as its factorization.

28239 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9416.

The product of its digits is 864, while the sum is 24.

The square root of 28239 is about 168.0446369272. The cubic root of 28239 is about 30.4520432407.

The spelling of 28239 in words is "twenty-eight thousand, two hundred thirty-nine".