18221449 has 4 divisors (see below), whose sum is σ = 18231364. Its totient is φ = 18211536.

The previous prime is 18221443. The next prime is 18221471. The reversal of 18221449 is 94412281.

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, and also an emirpimes, since its reverse is a distinct semiprime: 94412281 = 167 ⋅565343.

It can be written as a sum of positive squares in 2 ways, for example, as 17305600 + 915849 = 4160^2 + 957^2 .

It is a cyclic number.

It is not a de Polignac number, because 18221449 - 2⁵ = 18221417 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 18221449.

It is not an unprimeable number, because it can be changed into a prime (18221443) 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, 1302 + ... + 6175.

It is an arithmetic number, because the mean of its divisors is an integer number (4557841).

Almost surely, 2^18221449 is an apocalyptic number.

It is an amenable number.

18221449 is a deficient number, since it is larger than the sum of its proper divisors (9915).

18221449 is an equidigital number, since it uses as much as digits as its factorization.

18221449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9914.

The product of its digits is 4608, while the sum is 31.

The square root of 18221449 is about 4268.6589228937. The cubic root of 18221449 is about 263.1445036632.

The spelling of 18221449 in words is "eighteen million, two hundred twenty-one thousand, four hundred forty-nine".