Take a gamble

Let \(S\) be the set of all 21-digit positive integers that can be composed from the digits \(1,2,3,4,5,6,7,8,9\) (repetition is of course allowed, but not all digits must necessarily appear). Let \(N\) be an element of \(S\) chosen uniformly at random, and let \(A\) be the product of all the digits of \(N\).

If \(P\) is the probability that \(A\) is divisible by \(21\), then find \(\lfloor 1000P \rfloor\).

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