18805909 has 4 divisors (see below), whose sum is σ = 18815500. Its totient is φ = 18796320.

The previous prime is 18805907. The next prime is 18805939. The reversal of 18805909 is 90950881.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90950881 = 7 ⋅12992983.

It can be written as a sum of positive squares in 2 ways, for example, as 7896100 + 10909809 = 2810^2 + 3303^2 .

It is a cyclic number.

It is not a de Polignac number, because 18805909 - 2¹ = 18805907 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 (18805903) 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, 672 + ... + 6169.

It is an arithmetic number, because the mean of its divisors is an integer number (4703875).

Almost surely, 2^18805909 is an apocalyptic number.

It is an amenable number.

18805909 is a deficient number, since it is larger than the sum of its proper divisors (9591).

18805909 is an equidigital number, since it uses as much as digits as its factorization.

18805909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9590.

The product of its (nonzero) digits is 25920, while the sum is 40.

The square root of 18805909 is about 4336.5780288149. The cubic root of 18805909 is about 265.9284344004.

The spelling of 18805909 in words is "eighteen million, eight hundred five thousand, nine hundred nine".