18663538 has 4 divisors (see below), whose sum is σ = 27995310. Its totient is φ = 9331768.

The previous prime is 18663527. The next prime is 18663553. The reversal of 18663538 is 83536681.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 13155129 + 5508409 = 3627^2 + 2347^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 18663538.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4665883 + ... + 4665886.

Almost surely, 2^18663538 is an apocalyptic number.

18663538 is a deficient number, since it is larger than the sum of its proper divisors (9331772).

18663538 is an equidigital number, since it uses as much as digits as its factorization.

18663538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9331771.

The product of its digits is 103680, while the sum is 40.

The square root of 18663538 is about 4320.1317109551. The cubic root of 18663538 is about 265.2556592892.

The spelling of 18663538 in words is "eighteen million, six hundred sixty-three thousand, five hundred thirty-eight".