18221812 has 12 divisors (see below), whose sum is σ = 36443680. Its totient is φ = 7809336.

The previous prime is 18221783. The next prime is 18221821. The reversal of 18221812 is 21812281.

18221812 is an admirable number.

It is a congruent number.

It is an unprimeable number.

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, 325362 + ... + 325417.

Almost surely, 2^18221812 is an apocalyptic number.

It is an amenable number.

18221812 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18221812 is a wasteful number, since it uses less digits than its factorization.

18221812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 650790 (or 650788 counting only the distinct ones).

The product of its digits is 512, while the sum is 25.

The square root of 18221812 is about 4268.7014418907. The cubic root of 18221812 is about 263.1462510694.

The spelling of 18221812 in words is "eighteen million, two hundred twenty-one thousand, eight hundred twelve".