If  $h$  is the altitude of a parallelepiped determined by the vectors  $\overrightarrow{a},\overrightarrow{b},\overrightarrow{c}$ and the base is taken to be the parallelogram determined by $\overrightarrow{a}$  and $\overrightarrow{b}$  where $\overrightarrow{a}=\widehat{i}+\widehat{j}+\widehat{k},\overrightarrow{b}=2\widehat{i}+4\widehat{j}-\widehat{k}$  and $\overrightarrow{c}=\widehat{i}+\widehat{j}+3\widehat{k}$  then the value of $19h^2$ is