Una rolls $6$ standard $6$-sided dice simultaneously and calculates the product of the $6$ numbers obtained. What is the probability that the product is divisible by $4$? Provide your answer in the form of \(\frac{k}{m}\) where the fraction is in simplest form. Please give the value of \(k + m\).

Let's think step by step and output the final answer within \boxed{}.
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