28107221 has 4 divisors (see below), whose sum is σ = 28180992. Its totient is φ = 28033452.

The previous prime is 28107199. The next prime is 28107227. The reversal of 28107221 is 12270182.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28107221 - 2¹⁴ = 28090837 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28107227) 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, 36311 + ... + 37076.

It is an arithmetic number, because the mean of its divisors is an integer number (7045248).

Almost surely, 2^28107221 is an apocalyptic number.

It is an amenable number.

28107221 is a deficient number, since it is larger than the sum of its proper divisors (73771).

28107221 is an equidigital number, since it uses as much as digits as its factorization.

28107221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73770.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 28107221 is about 5301.6243737179. The cubic root of 28107221 is about 304.0460059932.

The spelling of 28107221 in words is "twenty-eight million, one hundred seven thousand, two hundred twenty-one".