18645689 has 2 divisors, whose sum is σ = 18645690. Its totient is φ = 18645688.

The previous prime is 18645673. The next prime is 18645691. The reversal of 18645689 is 98654681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12924025 + 5721664 = 3595^2 + 2392^2 .

It is an emirp because it is prime and its reverse (98654681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18645689 - 2⁴ = 18645673 is a prime.

Together with 18645691, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18645619) 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, 9322844 + 9322845.

It is an arithmetic number, because the mean of its divisors is an integer number (9322845).

Almost surely, 2^18645689 is an apocalyptic number.

It is an amenable number.

18645689 is a deficient number, since it is larger than the sum of its proper divisors (1).

18645689 is an equidigital number, since it uses as much as digits as its factorization.

18645689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 414720, while the sum is 47.

The square root of 18645689 is about 4318.0654233117. The cubic root of 18645689 is about 265.1710726410.

The spelling of 18645689 in words is "eighteen million, six hundred forty-five thousand, six hundred eighty-nine".