28804221 has 16 divisors (see below), whose sum is σ = 44145600. Its totient is φ = 18540144.

The previous prime is 28804207. The next prime is 28804229. The reversal of 28804221 is 12240882.

It is not a de Polignac number, because 28804221 - 2⁶ = 28804157 is a prime.

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

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28804229) 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, 17611 + ... + 19176.

It is an arithmetic number, because the mean of its divisors is an integer number (2759100).

Almost surely, 2^28804221 is an apocalyptic number.

It is an amenable number.

28804221 is a deficient number, since it is larger than the sum of its proper divisors (15341379).

28804221 is a wasteful number, since it uses less digits than its factorization.

28804221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36825 (or 36819 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 28804221 is about 5366.9564000465. The cubic root of 28804221 is about 306.5387471894.

The spelling of 28804221 in words is "twenty-eight million, eight hundred four thousand, two hundred twenty-one".