18704221 has 4 divisors (see below), whose sum is σ = 19517472. Its totient is φ = 17890972.

The previous prime is 18704201. The next prime is 18704243. The reversal of 18704221 is 12240781.

It is a happy number.

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 18704221 - 2⁹ = 18703709 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 (18704201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 406591 + ... + 406636.

It is an arithmetic number, because the mean of its divisors is an integer number (4879368).

Almost surely, 2^18704221 is an apocalyptic number.

It is an amenable number.

18704221 is a deficient number, since it is larger than the sum of its proper divisors (813251).

18704221 is an equidigital number, since it uses as much as digits as its factorization.

18704221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813250.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 18704221 is about 4324.8376848155. The cubic root of 18704221 is about 265.4482552197.

The spelling of 18704221 in words is "eighteen million, seven hundred four thousand, two hundred twenty-one".