66206717478989 has 2 divisors, whose sum is σ = 66206717478990. Its totient is φ = 66206717478988.

The previous prime is 66206717478973. The next prime is 66206717479003. The reversal of 66206717478989 is 98987471760266.

It is a happy number.

66206717478989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53886126074089 + 12320591404900 = 7340717^2 + 3510070^2 .

It is a cyclic number.

It is not a de Polignac number, because 66206717478989 - 2⁴ = 66206717478973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66206717478929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33103358739494 + 33103358739495.

It is an arithmetic number, because the mean of its divisors is an integer number (33103358739495).

Almost surely, 2^{66206717478989} is an apocalyptic number.

It is an amenable number.

66206717478989 is a deficient number, since it is larger than the sum of its proper divisors (1).

66206717478989 is an equidigital number, since it uses as much as digits as its factorization.

66206717478989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3072577536, while the sum is 80.

The spelling of 66206717478989 in words is "sixty-six trillion, two hundred six billion, seven hundred seventeen million, four hundred seventy-eight thousand, nine hundred eighty-nine".