The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -89.47\\[1 em]x_2 &= -90.1959\\[1 em]x_3 &= 179.6659 \end{aligned} $$Polynomial $ x^3-24210x-1449872 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.