18284221 has 4 divisors (see below), whose sum is σ = 18294844. Its totient is φ = 18273600.

The previous prime is 18284219. The next prime is 18284257. The reversal of 18284221 is 12248281.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 13505625 + 4778596 = 3675^2 + 2186^2 .

It is a cyclic number.

It is not a de Polignac number, because 18284221 - 2¹ = 18284219 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18284221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18284261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2070 + ... + 6391.

It is an arithmetic number, because the mean of its divisors is an integer number (4573711).

Almost surely, 2^18284221 is an apocalyptic number.

It is an amenable number.

18284221 is a deficient number, since it is larger than the sum of its proper divisors (10623).

18284221 is an equidigital number, since it uses as much as digits as its factorization.

18284221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10622.

The product of its digits is 2048, while the sum is 28.

The square root of 18284221 is about 4276.0052619238. The cubic root of 18284221 is about 263.4463306470.

The spelling of 18284221 in words is "eighteen million, two hundred eighty-four thousand, two hundred twenty-one".