6686509 has 2 divisors, whose sum is σ = 6686510. Its totient is φ = 6686508.

The previous prime is 6686507. The next prime is 6686527. The reversal of 6686509 is 9056866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5745609 + 940900 = 2397^2 + 970^2 .

It is a cyclic number.

It is not a de Polignac number, because 6686509 - 2¹ = 6686507 is a prime.

Together with 6686507, 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 (6686507) 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, 3343254 + 3343255.

It is an arithmetic number, because the mean of its divisors is an integer number (3343255).

Almost surely, 2^6686509 is an apocalyptic number.

It is an amenable number.

6686509 is a deficient number, since it is larger than the sum of its proper divisors (1).

6686509 is an equidigital number, since it uses as much as digits as its factorization.

6686509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 77760, while the sum is 40.

The square root of 6686509 is about 2585.8284939261. The cubic root of 6686509 is about 188.3937443361.

The spelling of 6686509 in words is "six million, six hundred eighty-six thousand, five hundred nine".