The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -5.1356\\[1 em]x_2 &= 2.5678+24.7746i\\[1 em]x_3 &= 2.5678-24.7746i \end{aligned} $$Polynomial $ x^3+594x+3186 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.