18563 has 4 divisors (see below), whose sum is σ = 19560. Its totient is φ = 17568.

The previous prime is 18553. The next prime is 18583. The reversal of 18563 is 36581.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 36581 = 157 ⋅233.

It is a cyclic number.

It is not a de Polignac number, because 18563 - 2⁸ = 18307 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (18503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 470 + ... + 507.

It is an arithmetic number, because the mean of its divisors is an integer number (4890).

2¹⁸⁵⁶³ is an apocalyptic number.

18563 is a deficient number, since it is larger than the sum of its proper divisors (997).

18563 is an equidigital number, since it uses as much as digits as its factorization.

18563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 996.

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

The square root of 18563 is about 136.2461008616. The cubic root of 18563 is about 26.4778502467.

The spelling of 18563 in words is "eighteen thousand, five hundred sixty-three".