18705689 has 2 divisors, whose sum is σ = 18705690. Its totient is φ = 18705688.

The previous prime is 18705677. The next prime is 18705691. The reversal of 18705689 is 98650781.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18705625 + 64 = 4325^2 + 8^2 .

It is a cyclic number.

It is not a de Polignac number, because 18705689 - 2¹² = 18701593 is a prime.

It is a Sophie Germain prime.

Together with 18705691, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (18705629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9352844 + 9352845.

It is an arithmetic number, because the mean of its divisors is an integer number (9352845).

Almost surely, 2^18705689 is an apocalyptic number.

It is an amenable number.

18705689 is a deficient number, since it is larger than the sum of its proper divisors (1).

18705689 is an equidigital number, since it uses as much as digits as its factorization.

18705689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120960, while the sum is 44.

The square root of 18705689 is about 4325.0073988376. The cubic root of 18705689 is about 265.4551996030.

The spelling of 18705689 in words is "eighteen million, seven hundred five thousand, six hundred eighty-nine".