18985609 has 4 divisors (see below), whose sum is σ = 19598080. Its totient is φ = 18373140.

The previous prime is 18985601. The next prime is 18985619. The reversal of 18985609 is 90658981.

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, and also an emirpimes, since its reverse is a distinct semiprime: 90658981 = 7 ⋅12951283.

It is a cyclic number.

It is not a de Polignac number, because 18985609 - 2³ = 18985601 is a prime.

It is a super-4 number, since 4×18985609⁴ (a number of 30 digits) contains 4444 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18985601) 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, 306189 + ... + 306250.

It is an arithmetic number, because the mean of its divisors is an integer number (4899520).

Almost surely, 2^18985609 is an apocalyptic number.

It is an amenable number.

18985609 is a deficient number, since it is larger than the sum of its proper divisors (612471).

18985609 is an equidigital number, since it uses as much as digits as its factorization.

18985609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 612470.

The product of its (nonzero) digits is 155520, while the sum is 46.

The square root of 18985609 is about 4357.2478699289. The cubic root of 18985609 is about 266.7727777363.

The spelling of 18985609 in words is "eighteen million, nine hundred eighty-five thousand, six hundred nine".