18666709 has 2 divisors, whose sum is σ = 18666710. Its totient is φ = 18666708.

The previous prime is 18666707. The next prime is 18666733. The reversal of 18666709 is 90766681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18464209 + 202500 = 4297^2 + 450^2 .

It is a cyclic number.

It is not a de Polignac number, because 18666709 - 2¹ = 18666707 is a prime.

Together with 18666707, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18666707) by changing a digit.

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

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9333354 + 9333355.

It is an arithmetic number, because the mean of its divisors is an integer number (9333355).

Almost surely, 2^18666709 is an apocalyptic number.

It is an amenable number.

18666709 is a deficient number, since it is larger than the sum of its proper divisors (1).

18666709 is an equidigital number, since it uses as much as digits as its factorization.

18666709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 108864, while the sum is 43.

The square root of 18666709 is about 4320.4986980672. The cubic root of 18666709 is about 265.2706810581.

The spelling of 18666709 in words is "eighteen million, six hundred sixty-six thousand, seven hundred nine".