18918791 has 2 divisors, whose sum is σ = 18918792. Its totient is φ = 18918790.

The previous prime is 18918751. The next prime is 18918793. The reversal of 18918791 is 19781981.

It is a strong prime.

It is an emirp because it is prime and its reverse (19781981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18918791 - 2⁶ = 18918727 is a prime.

Together with 18918793, 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 (18918793) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459395 + 9459396.

It is an arithmetic number, because the mean of its divisors is an integer number (9459396).

Almost surely, 2^18918791 is an apocalyptic number.

18918791 is a deficient number, since it is larger than the sum of its proper divisors (1).

18918791 is an equidigital number, since it uses as much as digits as its factorization.

18918791 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 44.

The square root of 18918791 is about 4349.5736572680. The cubic root of 18918791 is about 266.4594496111.

The spelling of 18918791 in words is "eighteen million, nine hundred eighteen thousand, seven hundred ninety-one".