Question 20The number $21!$ $=51{,}090{,}942{,}171{,}709{,}440{,}000$ has over $60{,}000$ positive integer divisors. One of them is chosen at random. What is the probability that it is odd?$\dfrac{1}{21} $$\dfrac{1}{19} $$\dfrac{1}{18} $$\dfrac{1}{2} $$\dfrac{11}{21} $