18643 has 4 divisors (see below), whose sum is σ = 18928. Its totient is φ = 18360.

The previous prime is 18637. The next prime is 18661. The reversal of 18643 is 34681.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 34681 = 79 ⋅439.

It is a cyclic number.

It is not a de Polignac number, because 18643 - 2⁹ = 18131 is a prime.

It is a super-2 number, since 2×18643² = 695122898, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (18043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13 + ... + 193.

It is an arithmetic number, because the mean of its divisors is an integer number (4732).

2¹⁸⁶⁴³ is an apocalyptic number.

18643 is a deficient number, since it is larger than the sum of its proper divisors (285).

18643 is a wasteful number, since it uses less digits than its factorization.

18643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284.

The product of its digits is 576, while the sum is 22.

The square root of 18643 is about 136.5393716113. The cubic root of 18643 is about 26.5158324756.

The spelling of 18643 in words is "eighteen thousand, six hundred forty-three".