28905 has 16 divisors (see below), whose sum is σ = 48384. Its totient is φ = 14720.

The previous prime is 28901. The next prime is 28909. The reversal of 28905 is 50982.

28905 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (28901) and next prime (28909).

It is not a de Polignac number, because 28905 - 2² = 28901 is a prime.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

28905 is a lucky number.

It is a plaindrome in base 12.

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 (28901) 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, 592 + ... + 638.

It is an arithmetic number, because the mean of its divisors is an integer number (3024).

2²⁸⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

28905 is a deficient number, since it is larger than the sum of its proper divisors (19479).

28905 is a wasteful number, since it uses less digits than its factorization.

28905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 28905 is about 170.0147052463. The cubic root of 28905 is about 30.6895832697.

The spelling of 28905 in words is "twenty-eight thousand, nine hundred five".