Complexity of the following function $ f(n) = 1000+\log_{2}(n^{9n})+3n\log_{1000}(n^{n}) $


I know that $ f(n) = 1000+\log_{2}(n^{9n})+3n\log_{1000}(n^{n}) \in O(n^2\log{n}) $ , but how can you derive this. I mean you choose the strongest increasing term with the $ n$ in it and then you remove all the constants and that is you complexity but I do not know how to derive the above function. Can someone help me out?