28685 has 4 divisors (see below), whose sum is σ = 34428. Its totient is φ = 22944.

The previous prime is 28669. The next prime is 28687. The reversal of 28685 is 58682.

It is a happy number.

28685 is nontrivially palindromic in base 4.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3721 + 24964 = 61^2 + 158^2 .

It is a cyclic number.

It is not a de Polignac number, because 28685 - 2⁴ = 28669 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28687) 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, 2864 + ... + 2873.

It is an arithmetic number, because the mean of its divisors is an integer number (8607).

2²⁸⁶⁸⁵ is an apocalyptic number.

It is an amenable number.

28685 is a deficient number, since it is larger than the sum of its proper divisors (5743).

28685 is an equidigital number, since it uses as much as digits as its factorization.

28685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5742.

The product of its digits is 3840, while the sum is 29.

The square root of 28685 is about 169.3664665747. The cubic root of 28685 is about 30.6115239891.

It can be divided in two parts, 286 and 85, that multiplied together give a triangular number (24310 = T₂₂₀).

The spelling of 28685 in words is "twenty-eight thousand, six hundred eighty-five".