18666824509 has 2 divisors, whose sum is σ = 18666824510. Its totient is φ = 18666824508.

The previous prime is 18666824503. The next prime is 18666824543. The reversal of 18666824509 is 90542866681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18581779225 + 85045284 = 136315^2 + 9222^2 .

It is a cyclic number.

It is not a de Polignac number, because 18666824509 - 2⁹ = 18666823997 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18666824509.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18666824503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9333412254 + 9333412255.

It is an arithmetic number, because the mean of its divisors is an integer number (9333412255).

Almost surely, 2^18666824509 is an apocalyptic number.

It is an amenable number.

18666824509 is a deficient number, since it is larger than the sum of its proper divisors (1).

18666824509 is an equidigital number, since it uses as much as digits as its factorization.

18666824509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4976640, while the sum is 55.

The spelling of 18666824509 in words is "eighteen billion, six hundred sixty-six million, eight hundred twenty-four thousand, five hundred nine".