66618917 has 2 divisors, whose sum is σ = 66618918. Its totient is φ = 66618916.

The previous prime is 66618913. The next prime is 66618931. The reversal of 66618917 is 71981666.

66618917 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45144961 + 21473956 = 6719^2 + 4634^2 .

It is a cyclic number.

It is not a de Polignac number, because 66618917 - 2² = 66618913 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66618913) 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, 33309458 + 33309459.

It is an arithmetic number, because the mean of its divisors is an integer number (33309459).

Almost surely, 2^66618917 is an apocalyptic number.

It is an amenable number.

66618917 is a deficient number, since it is larger than the sum of its proper divisors (1).

66618917 is an equidigital number, since it uses as much as digits as its factorization.

66618917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 44.

The square root of 66618917 is about 8162.0412275362. The cubic root of 66618917 is about 405.3833022104.

The spelling of 66618917 in words is "sixty-six million, six hundred eighteen thousand, nine hundred seventeen".