18971 has 4 divisors (see below), whose sum is σ = 19344. Its totient is φ = 18600.

The previous prime is 18959. The next prime is 18973. The reversal of 18971 is 17981.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18971 is a prime.

It is a Duffinian number.

It is a plaindrome in base 6.

It is a self number, because there is not a number n which added to its sum of digits gives 18971.

It is not an unprimeable number, because it can be changed into a prime (18973) 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, 95 + ... + 216.

It is an arithmetic number, because the mean of its divisors is an integer number (4836).

2¹⁸⁹⁷¹ is an apocalyptic number.

18971 is a deficient number, since it is larger than the sum of its proper divisors (373).

18971 is an equidigital number, since it uses as much as digits as its factorization.

18971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 372.

The product of its digits is 504, while the sum is 26.

The square root of 18971 is about 137.7352532941. The cubic root of 18971 is about 26.6704334957.

Subtracting from 18971 its reverse (17981), we obtain a triangular number (990 = T₄₄).

It can be divided in two parts, 18 and 971, that added together give a palindrome (989).

The spelling of 18971 in words is "eighteen thousand, nine hundred seventy-one".