what is (6207/5400)1/7 (1 over 7)

I don't really understand your question

If you mean 1/7(6207/5400), then you can just multiply the numerators to get your new numerator, and  multiply the denominators to get your new denominators. 1*6207=6207, and 7*5400=37800. Your answer is 6207/37800.