66500009 has 2 divisors, whose sum is σ = 66500010. Its totient is φ = 66500008.

The previous prime is 66500003. The next prime is 66500011. The reversal of 66500009 is 90000566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 46963609 + 19536400 = 6853^2 + 4420^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66500009 is a prime.

Together with 66500011, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66500003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33250004 + 33250005.

It is an arithmetic number, because the mean of its divisors is an integer number (33250005).

Almost surely, 2^66500009 is an apocalyptic number.

It is an amenable number.

66500009 is a deficient number, since it is larger than the sum of its proper divisors (1).

66500009 is an equidigital number, since it uses as much as digits as its factorization.

66500009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1620, while the sum is 26.

The square root of 66500009 is about 8154.7537669754. The cubic root of 66500009 is about 405.1419692293.

The spelling of 66500009 in words is "sixty-six million, five hundred thousand, nine".