120 ('p' to the 17th power) = (4 x 30) x ('p' to the 16th power) x ('p')
The square root of all that is √4 x √30 x √('p' to the 16th power) x √p
Take the square roots of the ones you know: 2 x √30 x ('p' to the 8th power) x √p
So finally, it's
2 ('p' to the 8th power) √(30 p) .
