28428 has 24 divisors (see below), whose sum is σ = 69888. Its totient is φ = 8976.

The previous prime is 28411. The next prime is 28429. The reversal of 28428 is 82482.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 28398 and 28407.

It is not an unprimeable number, because it can be changed into a prime (28429) by changing a digit.

28428 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 7 ways as a sum of consecutive naturals, for example, 225 + ... + 327.

It is an arithmetic number, because the mean of its divisors is an integer number (2912).

2²⁸⁴²⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28428, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34944).

28428 is an abundant number, since it is smaller than the sum of its proper divisors (41460).

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

28428 is a wasteful number, since it uses less digits than its factorization.

28428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133 (or 131 counting only the distinct ones).

The product of its digits is 1024, while the sum is 24.

The square root of 28428 is about 168.6060497135. The cubic root of 28428 is about 30.5198294415.

It can be divided in two parts, 2842 and 8, that added together give a triangular number (2850 = T₇₅).

The spelling of 28428 in words is "twenty-eight thousand, four hundred twenty-eight".