Yes, employing the conversion formula \[1\ mg\ \ =\ \ \frac{1}{1000}\times 1\ g\]  “5550mg”, can be converted to the corresponding “gram” in the following way.

\begin{aligned}

  1 \mathrm{mg} & =\frac{1}{1000} \times 1 \mathrm{~g} \\

\therefore 5550 \mathrm{mg} & =5550 \times\left\{\frac{1}{1000} \times 1 \mathrm{~g}\right\} \\

& =5550 \times \frac{1}{1000} \times 1 \mathrm{~g} \\

& =5.55 \mathrm{~g}

\end{aligned}

So, there are “5.55g” in “5550mg”.