18004399 has 4 divisors (see below), whose sum is σ = 20576464. Its totient is φ = 15432336.

The previous prime is 18004379. The next prime is 18004417. The reversal of 18004399 is 99340081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99340081 = 5171 ⋅19211.

It is a cyclic number.

It is not a de Polignac number, because 18004399 - 2⁵ = 18004367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18004319) 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, 1286022 + ... + 1286035.

It is an arithmetic number, because the mean of its divisors is an integer number (5144116).

Almost surely, 2^18004399 is an apocalyptic number.

18004399 is a deficient number, since it is larger than the sum of its proper divisors (2572065).

18004399 is an equidigital number, since it uses as much as digits as its factorization.

18004399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2572064.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 18004399 is about 4243.1590825704. The cubic root of 18004399 is about 262.0954870179.

The spelling of 18004399 in words is "eighteen million, four thousand, three hundred ninety-nine".