So you can say that (x-(-2i))(x-1/3)(x-5) divides the polynomial.
What about the 4th factor ? Since the coefficients are integers, if a complex number (like -2i) is a root, then its conjugate is also a root.
The conjugate of a complex number a+ib is a-ib. Here, a=0 and b=-2. Can you do it ?