28820 has 24 divisors (see below), whose sum is σ = 66528. Its totient is φ = 10400.

The previous prime is 28817. The next prime is 28837. The reversal of 28820 is 2882.

28820 = T₉₅ + T₉₆ + ... + T₁₀₀.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 28792 and 28801.

It is a congruent 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, 155 + ... + 285.

It is an arithmetic number, because the mean of its divisors is an integer number (2772).

2²⁸⁸²⁰ is an apocalyptic number.

28820 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 28820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33264).

28820 is an abundant number, since it is smaller than the sum of its proper divisors (37708).

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

28820 is a wasteful number, since it uses less digits than its factorization.

28820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 28820 is about 169.7645428233. The cubic root of 28820 is about 30.6594711116.

28820 divided by its sum of digits (20) gives a palindrome (1441).

It can be divided in two parts, 28 and 820, that added together give a palindrome (848).

The spelling of 28820 in words is "twenty-eight thousand, eight hundred twenty".