18520809 has 4 divisors (see below), whose sum is σ = 24694416. Its totient is φ = 12347204.

The previous prime is 18520793. The next prime is 18520829. The reversal of 18520809 is 90802581.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18520809 - 2⁴ = 18520793 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18520809.

It is not an unprimeable number, because it can be changed into a prime (18520829) 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 3 ways as a sum of consecutive naturals, for example, 3086799 + ... + 3086804.

It is an arithmetic number, because the mean of its divisors is an integer number (6173604).

Almost surely, 2^18520809 is an apocalyptic number.

It is an amenable number.

18520809 is a deficient number, since it is larger than the sum of its proper divisors (6173607).

18520809 is an equidigital number, since it uses as much as digits as its factorization.

18520809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6173606.

The product of its (nonzero) digits is 5760, while the sum is 33.

The square root of 18520809 is about 4303.5809507897. The cubic root of 18520809 is about 264.5777492832.

The spelling of 18520809 in words is "eighteen million, five hundred twenty thousand, eight hundred nine".