Rewrite the expression to have a denominator that is a power of 10:

$\dfrac{1}{2^{11} \cdot 5^{17}} = \dfrac{1}{2^{11} \cdot 5^{17}} \times \dfrac{2^6}{2^6} = \dfrac{2^6}{2^{17} \cdot 5^{17}} = \dfrac{64}{10^{17}}$

So the decimal is $\dfrac{64}{10^{17}} = 0.\underbrace{00\ldots0}_{15}64$

The nonzero digits are $6$ and $4$ — that is, two nonzero digits.