Answer:
-i
Step-by-step explanation:
(-i)^0 = 1
(-i)^1 = -i
(-i)^2 = -1
(-i)^3 = -i
(-i)^4 = 1
(-i)^5 = -i
etc.
From this pattern, you see that when the exponent is a multiple of 4, you get 1. When the exponent is a multiple of 4 plus 1, you get -i, etc.
213 = 4 * 53 + 1
213 is 1 more than a multiple of 4.
(-i)^213 = (-i)^1 = -i