18404809 has 4 divisors (see below), whose sum is σ = 18422404. Its totient is φ = 18387216.

The previous prime is 18404797. The next prime is 18404839. The reversal of 18404809 is 90840481.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2975625 + 15429184 = 1725^2 + 3928^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18404809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18404839) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7122 + ... + 9355.

It is an arithmetic number, because the mean of its divisors is an integer number (4605601).

Almost surely, 2^18404809 is an apocalyptic number.

It is an amenable number.

18404809 is a deficient number, since it is larger than the sum of its proper divisors (17595).

18404809 is a wasteful number, since it uses less digits than its factorization.

18404809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17594.

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 18404809 is about 4290.0826332368. The cubic root of 18404809 is about 264.0242220276.

The spelling of 18404809 in words is "eighteen million, four hundred four thousand, eight hundred nine".