28638 has 24 divisors (see below), whose sum is σ = 65208. Its totient is φ = 9072.

The previous prime is 28631. The next prime is 28643. The reversal of 28638 is 83682.

28638 is a `hidden beast` number, since 28 + 638 = 666.

It is an Ulam 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 (28631) by changing a digit.

28638 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 645 + ... + 687.

It is an arithmetic number, because the mean of its divisors is an integer number (2717).

2²⁸⁶³⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32604).

28638 is an abundant number, since it is smaller than the sum of its proper divisors (36570).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28638 is a wasteful number, since it uses less digits than its factorization.

28638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88 (or 85 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 28638 is about 169.2276573140. The cubic root of 28638 is about 30.5947959880.

It can be divided in two parts, 286 and 38, that added together give a square (324 = 18²).

The spelling of 28638 in words is "twenty-eight thousand, six hundred thirty-eight".