16668696509 has 2 divisors, whose sum is σ = 16668696510. Its totient is φ = 16668696508.

The previous prime is 16668696491. The next prime is 16668696511. The reversal of 16668696509 is 90569686661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9376048900 + 7292647609 = 96830^2 + 85397^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16668696509 is a prime.

Together with 16668696511, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16668696529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8334348254 + 8334348255.

It is an arithmetic number, because the mean of its divisors is an integer number (8334348255).

Almost surely, 2^16668696509 is an apocalyptic number.

It is an amenable number.

16668696509 is a deficient number, since it is larger than the sum of its proper divisors (1).

16668696509 is an equidigital number, since it uses as much as digits as its factorization.

16668696509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25194240, while the sum is 62.

The spelling of 16668696509 in words is "sixteen billion, six hundred sixty-eight million, six hundred ninety-six thousand, five hundred nine".