In general relativity, a mass $M$ in kilograms is expressed in units of length as $M' = \frac{GM}{c^2}$. What is the geometrized mass of the Earth ($M_E \approx 5.9722 \times 10^{24} \text{ kg}$) in millimeters? (Take $G \approx 6.6743 \times 10^{-11} \text{ m}^3\text{kg}^{-1}\text{s}^{-2}$ and $c \approx 2.9979 \times 10^8 \text{ m/s}$)