18380209 has 4 divisors (see below), whose sum is σ = 18391104. Its totient is φ = 18369316.

The previous prime is 18380203. The next prime is 18380233. The reversal of 18380209 is 90208381.

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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90208381 = 1051 ⋅85831.

It is a cyclic number.

It is not a de Polignac number, because 18380209 - 2¹⁷ = 18249137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18380203) 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, 2317 + ... + 6490.

It is an arithmetic number, because the mean of its divisors is an integer number (4597776).

Almost surely, 2^18380209 is an apocalyptic number.

It is an amenable number.

18380209 is a deficient number, since it is larger than the sum of its proper divisors (10895).

18380209 is an equidigital number, since it uses as much as digits as its factorization.

18380209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10894.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 18380209 is about 4287.2145969149. The cubic root of 18380209 is about 263.9065373550.

The spelling of 18380209 in words is "eighteen million, three hundred eighty thousand, two hundred nine".