18363221 has 4 divisors (see below), whose sum is σ = 18378444. Its totient is φ = 18348000.

The previous prime is 18363217. The next prime is 18363239. The reversal of 18363221 is 12236381.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16080100 + 2283121 = 4010^2 + 1511^2 .

It is a cyclic number.

It is not a de Polignac number, because 18363221 - 2² = 18363217 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 (18363251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5630 + ... + 8271.

It is an arithmetic number, because the mean of its divisors is an integer number (4594611).

Almost surely, 2^18363221 is an apocalyptic number.

It is an amenable number.

18363221 is a deficient number, since it is larger than the sum of its proper divisors (15223).

18363221 is a wasteful number, since it uses less digits than its factorization.

18363221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15222.

The product of its digits is 1728, while the sum is 26.

The square root of 18363221 is about 4285.2328991550. The cubic root of 18363221 is about 263.8252066479.

The spelling of 18363221 in words is "eighteen million, three hundred sixty-three thousand, two hundred twenty-one".