18605809 has 4 divisors (see below), whose sum is σ = 18956916. Its totient is φ = 18254704.

The previous prime is 18605801. The next prime is 18605863. The reversal of 18605809 is 90850681.

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 12215025 + 6390784 = 3495^2 + 2528^2 .

It is a cyclic number.

It is not a de Polignac number, because 18605809 - 2³ = 18605801 is a prime.

It is a super-2 number, since 2×18605809² = 692352257088962, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18605801) 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, 175474 + ... + 175579.

It is an arithmetic number, because the mean of its divisors is an integer number (4739229).

Almost surely, 2^18605809 is an apocalyptic number.

It is an amenable number.

18605809 is a deficient number, since it is larger than the sum of its proper divisors (351107).

18605809 is an equidigital number, since it uses as much as digits as its factorization.

18605809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351106.

The product of its (nonzero) digits is 17280, while the sum is 37.

The square root of 18605809 is about 4313.4451428064. The cubic root of 18605809 is about 264.9818855542.

The spelling of 18605809 in words is "eighteen million, six hundred five thousand, eight hundred nine".