From now on I will. Thanks for suggesting.
It can be a bit subtle to get Wolfram|Alpha to know what one is asking. If it doesn't respond properly to a sensibly phrased query it's always good to submit a report: they are taken seriously and used to update Wolfram|Alpha's parser.
Ach. Thanks! I was close though - tried this one as the first guess:
2547th prime from 982400000
This works in Woflram|Alpha
2547th prime after 982400000
http://www.wolframalpha.com/input/?i=2547th+prime+after+982400000
Select[Range[982400000 , 982500000], PrimeQ][[2547]]
gives
982451653
