18397221 has 8 divisors (see below), whose sum is σ = 24677184. Its totient is φ = 12191040.

The previous prime is 18397207. The next prime is 18397231. The reversal of 18397221 is 12279381.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18397221 - 2⁶ = 18397157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18397231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17860 + ... + 18861.

It is an arithmetic number, because the mean of its divisors is an integer number (3084648).

Almost surely, 2^18397221 is an apocalyptic number.

It is an amenable number.

18397221 is a deficient number, since it is larger than the sum of its proper divisors (6279963).

18397221 is a wasteful number, since it uses less digits than its factorization.

18397221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36891.

The product of its digits is 6048, while the sum is 33.

The square root of 18397221 is about 4289.1981768158. The cubic root of 18397221 is about 263.9879327588.

The spelling of 18397221 in words is "eighteen million, three hundred ninety-seven thousand, two hundred twenty-one".