28228221 has 12 divisors (see below), whose sum is σ = 46599072. Its totient is φ = 16130376.

The previous prime is 28228169. The next prime is 28228229. The reversal of 28228221 is 12282282.

It is not a de Polignac number, because 28228221 - 2⁶ = 28228157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28228229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 223971 + ... + 224096.

It is an arithmetic number, because the mean of its divisors is an integer number (3883256).

Almost surely, 2^28228221 is an apocalyptic number.

28228221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28228221 is a deficient number, since it is larger than the sum of its proper divisors (18370851).

28228221 is a wasteful number, since it uses less digits than its factorization.

28228221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 448080 (or 448077 counting only the distinct ones).

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

The square root of 28228221 is about 5313.0237153621. The cubic root of 28228221 is about 304.4816817019.

The spelling of 28228221 in words is "twenty-eight million, two hundred twenty-eight thousand, two hundred twenty-one".