28222221 has 4 divisors (see below), whose sum is σ = 37629632. Its totient is φ = 18814812.

The previous prime is 28222217. The next prime is 28222223. The reversal of 28222221 is 12222282.

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 not a de Polignac number, because 28222221 - 2² = 28222217 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 (28222223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4703701 + ... + 4703706.

It is an arithmetic number, because the mean of its divisors is an integer number (9407408).

Almost surely, 2^28222221 is an apocalyptic number.

It is an amenable number.

28222221 is a deficient number, since it is larger than the sum of its proper divisors (9407411).

28222221 is an equidigital number, since it uses as much as digits as its factorization.

28222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9407410.

The product of its digits is 512, while the sum is 21.

The square root of 28222221 is about 5312.4590351362. The cubic root of 28222221 is about 304.4601073167.

The spelling of 28222221 in words is "twenty-eight million, two hundred twenty-two thousand, two hundred twenty-one".