18543209 has 12 divisors (see below), whose sum is σ = 20350044. Its totient is φ = 16837632.

The previous prime is 18543167. The next prime is 18543223. The reversal of 18543209 is 90234581.

It can be written as a sum of positive squares in 6 ways, for example, as 4853209 + 13690000 = 2203^2 + 3700^2 .

It is not a de Polignac number, because 18543209 - 2¹² = 18539113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18543229) 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, 13649 + ... + 14945.

It is an arithmetic number, because the mean of its divisors is an integer number (1695837).

Almost surely, 2^18543209 is an apocalyptic number.

It is an amenable number.

18543209 is a deficient number, since it is larger than the sum of its proper divisors (1806835).

18543209 is a wasteful number, since it uses less digits than its factorization.

18543209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1372 (or 1343 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 18543209 is about 4306.1826482396. The cubic root of 18543209 is about 264.6843708658.

The spelling of 18543209 in words is "eighteen million, five hundred forty-three thousand, two hundred nine".