18640209 has 8 divisors (see below), whose sum is σ = 28404160. Its totient is φ = 10651536.

The previous prime is 18640103. The next prime is 18640241. The reversal of 18640209 is 90204681.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-18640209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18640289) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 443794 + ... + 443835.

It is an arithmetic number, because the mean of its divisors is an integer number (3550520).

Almost surely, 2^18640209 is an apocalyptic number.

It is an amenable number.

18640209 is a deficient number, since it is larger than the sum of its proper divisors (9763951).

18640209 is an equidigital number, since it uses as much as digits as its factorization.

18640209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 887639.

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 18640209 is about 4317.4308332618. The cubic root of 18640209 is about 265.1450920178.

The spelling of 18640209 in words is "eighteen million, six hundred forty thousand, two hundred nine".