18209305 has 4 divisors (see below), whose sum is σ = 21851172. Its totient is φ = 14567440.

The previous prime is 18209231. The next prime is 18209309. The reversal of 18209305 is 50390281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50390281 = 43 ⋅1171867.

It can be written as a sum of positive squares in 2 ways, for example, as 13816089 + 4393216 = 3717^2 + 2096^2 .

It is not a de Polignac number, because 18209305 - 2⁹ = 18208793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18209309) 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, 1820926 + ... + 1820935.

It is an arithmetic number, because the mean of its divisors is an integer number (5462793).

Almost surely, 2^18209305 is an apocalyptic number.

It is an amenable number.

18209305 is a deficient number, since it is larger than the sum of its proper divisors (3641867).

18209305 is an equidigital number, since it uses as much as digits as its factorization.

18209305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3641866.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 18209305 is about 4267.2362250056. The cubic root of 18209305 is about 263.0860316020.

Adding to 18209305 its reverse (50390281), we get a palindrome (68599586).

The spelling of 18209305 in words is "eighteen million, two hundred nine thousand, three hundred five".