18003605 has 4 divisors (see below), whose sum is σ = 21604332. Its totient is φ = 14402880.

The previous prime is 18003599. The next prime is 18003607. The reversal of 18003605 is 50630081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50630081 = 4423 ⋅11447.

It can be written as a sum of positive squares in 2 ways, for example, as 12945604 + 5058001 = 3598^2 + 2249^2 .

It is not a de Polignac number, because 18003605 - 2⁴ = 18003589 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 (18003607) 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, 1800356 + ... + 1800365.

It is an arithmetic number, because the mean of its divisors is an integer number (5401083).

Almost surely, 2^18003605 is an apocalyptic number.

It is an amenable number.

18003605 is a deficient number, since it is larger than the sum of its proper divisors (3600727).

18003605 is an equidigital number, since it uses as much as digits as its factorization.

18003605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3600726.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 18003605 is about 4243.0655191736. The cubic root of 18003605 is about 262.0916341284.

Adding to 18003605 its reverse (50630081), we get a palindrome (68633686).

The spelling of 18003605 in words is "eighteen million, three thousand, six hundred five".