18917 has 2 divisors, whose sum is σ = 18918. Its totient is φ = 18916.

The previous prime is 18913. The next prime is 18919. The reversal of 18917 is 71981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17956 + 961 = 134^2 + 31^2 .

It is a cyclic number.

It is not a de Polignac number, because 18917 - 2² = 18913 is a prime.

Together with 18919, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9458 + 9459.

It is an arithmetic number, because the mean of its divisors is an integer number (9459).

2¹⁸⁹¹⁷ is an apocalyptic number.

It is an amenable number.

18917 is a deficient number, since it is larger than the sum of its proper divisors (1).

18917 is an equidigital number, since it uses as much as digits as its factorization.

18917 is an evil number, because the sum of its binary digits is even.

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

The square root of 18917 is about 137.5390853539. The cubic root of 18917 is about 26.6451040971.

The spelling of 18917 in words is "eighteen thousand, nine hundred seventeen".