66666084817 has 4 divisors (see below), whose sum is σ = 70587619236. Its totient is φ = 62744550400.

The previous prime is 66666084809. The next prime is 66666084827. The reversal of 66666084817 is 71848066666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 42888753216 + 23777331601 = 207096^2 + 154199^2 .

It is a cyclic number.

It is not a de Polignac number, because 66666084817 - 2³ = 66666084809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66666084827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1960767184 + ... + 1960767217.

It is an arithmetic number, because the mean of its divisors is an integer number (17646904809).

Almost surely, 2^66666084817 is an apocalyptic number.

It is an amenable number.

66666084817 is a deficient number, since it is larger than the sum of its proper divisors (3921534419).

66666084817 is a wasteful number, since it uses less digits than its factorization.

66666084817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3921534418.

The product of its (nonzero) digits is 13934592, while the sum is 58.

The spelling of 66666084817 in words is "sixty-six billion, six hundred sixty-six million, eighty-four thousand, eight hundred seventeen".