28840 has 32 divisors (see below), whose sum is σ = 74880. Its totient is φ = 9792.

The previous prime is 28837. The next prime is 28843. The reversal of 28840 is 4882.

It is an interprime number because it is at equal distance from previous prime (28837) and next prime (28843).

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors.

It is a nialpdrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28843) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 229 + ... + 331.

It is an arithmetic number, because the mean of its divisors is an integer number (2340).

2²⁸⁸⁴⁰ is an apocalyptic number.

28840 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 28840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37440).

28840 is an abundant number, since it is smaller than the sum of its proper divisors (46040).

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

28840 is a wasteful number, since it uses less digits than its factorization.

28840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

The square root of 28840 is about 169.8234377228. The cubic root of 28840 is about 30.6665616464. Note that the first 3 decimals are identical.

It can be divided in two parts, 28 and 840, that added together give a palindrome (868).

The spelling of 28840 in words is "twenty-eight thousand, eight hundred forty".