28518021 has 16 divisors (see below), whose sum is σ = 48284800. Its totient is φ = 16295904.

The previous prime is 28518013. The next prime is 28518043. The reversal of 28518021 is 12081582.

It is not a de Polignac number, because 28518021 - 2³ = 28518013 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28518071) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 75256 + ... + 75633.

It is an arithmetic number, because the mean of its divisors is an integer number (3017800).

Almost surely, 2^28518021 is an apocalyptic number.

28518021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28518021 is a deficient number, since it is larger than the sum of its proper divisors (19766779).

28518021 is a wasteful number, since it uses less digits than its factorization.

28518021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150905 (or 150899 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 28518021 is about 5340.2266805820. The cubic root of 28518021 is about 305.5201051446.

The spelling of 28518021 in words is "twenty-eight million, five hundred eighteen thousand, twenty-one".