66685789 has 4 divisors (see below), whose sum is σ = 66712860. Its totient is φ = 66658720.

The previous prime is 66685777. The next prime is 66685793. The reversal of 66685789 is 98758666.

It is a happy number.

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 37417689 + 29268100 = 6117^2 + 5410^2 .

It is a cyclic number.

It is not a de Polignac number, because 66685789 - 2⁵ = 66685757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66685739) 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 in 3 ways as a sum of consecutive naturals, for example, 9424 + ... + 14905.

It is an arithmetic number, because the mean of its divisors is an integer number (16678215).

Almost surely, 2^66685789 is an apocalyptic number.

It is an amenable number.

66685789 is a deficient number, since it is larger than the sum of its proper divisors (27071).

66685789 is a wasteful number, since it uses less digits than its factorization.

66685789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27070.

The product of its digits is 4354560, while the sum is 55.

The square root of 66685789 is about 8166.1367243024. The cubic root of 66685789 is about 405.5188979634.

The spelling of 66685789 in words is "sixty-six million, six hundred eighty-five thousand, seven hundred eighty-nine".