28040 has 16 divisors (see below), whose sum is σ = 63180. Its totient is φ = 11200.

The previous prime is 28031. The next prime is 28051. The reversal of 28040 is 4082.

It can be written as a sum of positive squares in 2 ways, for example, as 27556 + 484 = 166^2 + 22^2 .

It is a nialpdrome in base 8.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 311 + ... + 390.

2²⁸⁰⁴⁰ is an apocalyptic number.

28040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28040 is an abundant number, since it is smaller than the sum of its proper divisors (35140).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31590).

28040 is a wasteful number, since it uses less digits than its factorization.

28040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 712 (or 708 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 28040 is about 167.4514855115. The cubic root of 28040 is about 30.3803427860.

The spelling of 28040 in words is "twenty-eight thousand, forty".