28874221 has 4 divisors (see below), whose sum is σ = 28885500. Its totient is φ = 28862944.

The previous prime is 28874213. The next prime is 28874231. The reversal of 28874221 is 12247882.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12247882 = 2 ⋅6123941.

It can be written as a sum of positive squares in 2 ways, for example, as 11485321 + 17388900 = 3389^2 + 4170^2 .

It is a cyclic number.

It is not a de Polignac number, because 28874221 - 2³ = 28874213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28874231) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 255 + ... + 7603.

It is an arithmetic number, because the mean of its divisors is an integer number (7221375).

Almost surely, 2^28874221 is an apocalyptic number.

It is an amenable number.

28874221 is a deficient number, since it is larger than the sum of its proper divisors (11279).

28874221 is an equidigital number, since it uses as much as digits as its factorization.

28874221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11278.

The product of its digits is 14336, while the sum is 34.

The square root of 28874221 is about 5373.4738298423. The cubic root of 28874221 is about 306.7868630652.

The spelling of 28874221 in words is "twenty-eight million, eight hundred seventy-four thousand, two hundred twenty-one".