16668809 has 2 divisors, whose sum is σ = 16668810. Its totient is φ = 16668808.

The previous prime is 16668803. The next prime is 16668851. The reversal of 16668809 is 90886661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11075584 + 5593225 = 3328^2 + 2365^2 .

It is a cyclic number.

It is not a de Polignac number, because 16668809 - 2¹⁶ = 16603273 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16668809.

It is not a weakly prime, because it can be changed into another prime (16668803) 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, 8334404 + 8334405.

It is an arithmetic number, because the mean of its divisors is an integer number (8334405).

Almost surely, 2^16668809 is an apocalyptic number.

It is an amenable number.

16668809 is a deficient number, since it is larger than the sum of its proper divisors (1).

16668809 is an equidigital number, since it uses as much as digits as its factorization.

16668809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 124416, while the sum is 44.

The square root of 16668809 is about 4082.7452773838. The cubic root of 16668809 is about 255.4474215972.

The spelling of 16668809 in words is "sixteen million, six hundred sixty-eight thousand, eight hundred nine".