18918409 has 8 divisors (see below), whose sum is σ = 19689120. Its totient is φ = 18162816.

The previous prime is 18918373. The next prime is 18918413. The reversal of 18918409 is 90481981.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18918409 - 2⁹ = 18917897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18918499) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1192 + ... + 6265.

It is an arithmetic number, because the mean of its divisors is an integer number (2461140).

Almost surely, 2^18918409 is an apocalyptic number.

It is an amenable number.

18918409 is a deficient number, since it is larger than the sum of its proper divisors (770711).

18918409 is an equidigital number, since it uses as much as digits as its factorization.

18918409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7559.

The product of its (nonzero) digits is 20736, while the sum is 40.

The square root of 18918409 is about 4349.5297446965. The cubic root of 18918409 is about 266.4576561879.

The spelling of 18918409 in words is "eighteen million, nine hundred eighteen thousand, four hundred nine".