18028221 has 4 divisors (see below), whose sum is σ = 24037632. Its totient is φ = 12018812.

The previous prime is 18028189. The next prime is 18028229. The reversal of 18028221 is 12282081.

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 18028221 - 2⁵ = 18028189 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18028191 and 18028200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18028229) 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, 3004701 + ... + 3004706.

It is an arithmetic number, because the mean of its divisors is an integer number (6009408).

Almost surely, 2^18028221 is an apocalyptic number.

It is an amenable number.

18028221 is a deficient number, since it is larger than the sum of its proper divisors (6009411).

18028221 is an equidigital number, since it uses as much as digits as its factorization.

18028221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6009410.

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 18028221 is about 4245.9652612804. The cubic root of 18028221 is about 262.2110307621.

The spelling of 18028221 in words is "eighteen million, twenty-eight thousand, two hundred twenty-one".