18019989 has 40 divisors (see below), whose sum is σ = 29441720. Its totient is φ = 10917504.

The previous prime is 18019943. The next prime is 18019993. The reversal of 18019989 is 98991081.

It can be written as a sum of positive squares in 4 ways, for example, as 656100 + 17363889 = 810^2 + 4167^2 .

It is not a de Polignac number, because 18019989 - 2⁷ = 18019861 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18019909) 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 39 ways as a sum of consecutive naturals, for example, 114699 + ... + 114855.

It is an arithmetic number, because the mean of its divisors is an integer number (736043).

Almost surely, 2^18019989 is an apocalyptic number.

It is an amenable number.

18019989 is a deficient number, since it is larger than the sum of its proper divisors (11421731).

18019989 is a wasteful number, since it uses less digits than its factorization.

18019989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 291 (or 282 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 45.

The square root of 18019989 is about 4244.9957597152. The cubic root of 18019989 is about 262.1711146434.

The spelling of 18019989 in words is "eighteen million, nineteen thousand, nine hundred eighty-nine".