18559921 has 12 divisors (see below), whose sum is σ = 19442332. Its totient is φ = 17712000.

The previous prime is 18559909. The next prime is 18559927. The reversal of 18559921 is 12995581.

It can be written as a sum of positive squares in 6 ways, for example, as 16200625 + 2359296 = 4025^2 + 1536^2 .

It is not a de Polignac number, because 18559921 - 2⁵ = 18559889 is a prime.

It is a Duffinian number.

Its product of digits (32400) is a multiple of the sum of its prime factors (324).

It is not an unprimeable number, because it can be changed into a prime (18559927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 102451 + ... + 102631.

Almost surely, 2^18559921 is an apocalyptic number.

It is an amenable number.

18559921 is a deficient number, since it is larger than the sum of its proper divisors (882411).

18559921 is an equidigital number, since it uses as much as digits as its factorization.

18559921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324 (or 283 counting only the distinct ones).

The product of its digits is 32400, while the sum is 40.

The square root of 18559921 is about 4308.1226769905. The cubic root of 18559921 is about 264.7638622672.

It can be divided in two parts, 185 and 59921, that added together give a palindrome (60106).

The spelling of 18559921 in words is "eighteen million, five hundred fifty-nine thousand, nine hundred twenty-one".