28520 has 32 divisors (see below), whose sum is σ = 69120. Its totient is φ = 10560.

The previous prime is 28517. The next prime is 28537. The reversal of 28520 is 2582.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 905 + ... + 935.

It is an arithmetic number, because the mean of its divisors is an integer number (2160).

2²⁸⁵²⁰ is an apocalyptic number.

28520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34560).

28520 is an abundant number, since it is smaller than the sum of its proper divisors (40600).

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

28520 is a wasteful number, since it uses less digits than its factorization.

28520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65 (or 61 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 28520 is about 168.8786546607. The cubic root of 28520 is about 30.5527172142.

Adding to 28520 its product of nonzero digits (160), we get a triangular number (28680 = T₂₃₉).

The spelling of 28520 in words is "twenty-eight thousand, five hundred twenty".