18239221 has 48 divisors (see below), whose sum is σ = 26429760. Its totient is φ = 12337920.

The previous prime is 18239213. The next prime is 18239227. The reversal of 18239221 is 12293281.

It is not a de Polignac number, because 18239221 - 2³ = 18239213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18239221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18239227) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 133065 + ... + 133201.

It is an arithmetic number, because the mean of its divisors is an integer number (550620).

Almost surely, 2^18239221 is an apocalyptic number.

18239221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18239221 is a deficient number, since it is larger than the sum of its proper divisors (8190539).

18239221 is a wasteful number, since it uses less digits than its factorization.

18239221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194 (or 187 counting only the distinct ones).

The product of its digits is 1728, while the sum is 28.

The square root of 18239221 is about 4270.7400997954. The cubic root of 18239221 is about 263.2300271310.

The spelling of 18239221 in words is "eighteen million, two hundred thirty-nine thousand, two hundred twenty-one".