18763221 has 4 divisors (see below), whose sum is σ = 25017632. Its totient is φ = 12508812.

The previous prime is 18763207. The next prime is 18763231. The reversal of 18763221 is 12236781.

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 not a de Polignac number, because 18763221 - 2¹⁷ = 18632149 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18763231) 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, 3127201 + ... + 3127206.

It is an arithmetic number, because the mean of its divisors is an integer number (6254408).

Almost surely, 2^18763221 is an apocalyptic number.

It is an amenable number.

18763221 is a deficient number, since it is larger than the sum of its proper divisors (6254411).

18763221 is an equidigital number, since it uses as much as digits as its factorization.

18763221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6254410.

The product of its digits is 4032, while the sum is 30.

The square root of 18763221 is about 4331.6533794846. The cubic root of 18763221 is about 265.7270694426.

The spelling of 18763221 in words is "eighteen million, seven hundred sixty-three thousand, two hundred twenty-one".