19) $$(7 \cdot 10^{3})^{2} \cdot (16 \cdot 10^{-4})$$

$$\begin{aligned} & (7 \cdot 10^{3})^{2} \cdot (16 \cdot 10^{-4}) = \\ & = 7^2 \cdot (10^{3})^2 \cdot 16 \cdot 10^{-4} = \\ & = 49 \cdot 10^{6} \cdot 16 \cdot 10^{-4} = \\ & = 49 \cdot 16 \cdot 10^{6-4} = \\ & = 784 \cdot 10^{2} = \\ & = 78400 end{aligned}$$ $$\boxed{78400}$$