If you follow through on the reference you gave,
(and if I had followed it and looked at THEIR definitions for AL)
we see that AL is in nH, and we can just use the formula N = sqrt(10^9 x L /AL), with L in H.
In your case 12uH so
N = sqrt(10^9 x 12 x 10^-6 / 4160) = sqrt(2.88) = 1.69 turns.
Which leads to another problem, on a toroid you can only have whole turns, if the wire goes through the toroid, it is one turn.
So if you were to put two turns on your toroid you would have:
L = AL x N^2 = 4160 x 2^2 = 16600 nH = 16.6uH
JimB