18490221 has 16 divisors (see below), whose sum is σ = 28062720. Its totient is φ = 12025440.

The previous prime is 18490207. The next prime is 18490247. The reversal of 18490221 is 12209481.

It is not a de Polignac number, because 18490221 - 2⁵ = 18490189 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18490201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7245 + ... + 9458.

It is an arithmetic number, because the mean of its divisors is an integer number (1753920).

Almost surely, 2^18490221 is an apocalyptic number.

It is an amenable number.

18490221 is a deficient number, since it is larger than the sum of its proper divisors (9572499).

18490221 is a wasteful number, since it uses less digits than its factorization.

18490221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16753 (or 16747 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 18490221 is about 4300.0256975976. The cubic root of 18490221 is about 264.4320147644.

The spelling of 18490221 in words is "eighteen million, four hundred ninety thousand, two hundred twenty-one".