18398909 has 4 divisors (see below), whose sum is σ = 18424416. Its totient is φ = 18373404.

The previous prime is 18398899. The next prime is 18398911. The reversal of 18398909 is 90989381.

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: 90989381 = 7 ⋅12998483.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18398909 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18398309) 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, 11639 + ... + 13124.

It is an arithmetic number, because the mean of its divisors is an integer number (4606104).

Almost surely, 2^18398909 is an apocalyptic number.

It is an amenable number.

18398909 is a deficient number, since it is larger than the sum of its proper divisors (25507).

18398909 is an equidigital number, since it uses as much as digits as its factorization.

18398909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25506.

The product of its (nonzero) digits is 139968, while the sum is 47.

The square root of 18398909 is about 4289.3949456771. The cubic root of 18398909 is about 263.9960064058.

The spelling of 18398909 in words is "eighteen million, three hundred ninety-eight thousand, nine hundred nine".