Oh GOOD ...
Ahhh ... so it was a pattern of adding, subtracting or multiplying by the prime number sequence ... how devilish.
The pattern was:
Odd turn: (Even number: +, Odd number x)
Even turn: Even number: -, Odd number +)
Since the next prime number in the sequence was 37, and the next operation was multiply, then the answer was 1125 x 37 = 41625.
(The inherent problem with sequence questions, though, is that there can be multiple "right" answers.)