18189809 has 6 divisors (see below), whose sum is σ = 19993890. Its totient is φ = 16536080.

The previous prime is 18189793. The next prime is 18189823. The reversal of 18189809 is 90898181.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 17472400 + 717409 = 4180^2 + 847^2 .

It is not a de Polignac number, because 18189809 - 2⁴ = 18189793 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 18189809.

It is not an unprimeable number, because it can be changed into a prime (18189889) 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 5 ways as a sum of consecutive naturals, for example, 75044 + ... + 75285.

It is an arithmetic number, because the mean of its divisors is an integer number (3332315).

Almost surely, 2^18189809 is an apocalyptic number.

It is an amenable number.

18189809 is a deficient number, since it is larger than the sum of its proper divisors (1804081).

18189809 is a wasteful number, since it uses less digits than its factorization.

18189809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150351 (or 150340 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 44.

The square root of 18189809 is about 4264.9512306708. The cubic root of 18189809 is about 262.9921060535.

The spelling of 18189809 in words is "eighteen million, one hundred eighty-nine thousand, eight hundred nine".