18911 has 2 divisors, whose sum is σ = 18912. Its totient is φ = 18910.

The previous prime is 18899. The next prime is 18913. The reversal of 18911 is 11981.

It is a strong prime.

It is an emirp because it is prime and its reverse (11981) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18911 is a prime.

Together with 18913, it forms a pair of twin primes.

It is a Chen prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18913) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9455 + 9456.

It is an arithmetic number, because the mean of its divisors is an integer number (9456).

2¹⁸⁹¹¹ is an apocalyptic number.

18911 is the 62-nd centered decagonal number.

18911 is a deficient number, since it is larger than the sum of its proper divisors (1).

18911 is an equidigital number, since it uses as much as digits as its factorization.

18911 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72, while the sum is 20.

The square root of 18911 is about 137.5172716425. The cubic root of 18911 is about 26.6422867453.

It can be divided in two parts, 18 and 911, that added together give a palindrome (929).

The spelling of 18911 in words is "eighteen thousand, nine hundred eleven".