Let $\overrightarrow{\mathrm{a}}=\widehat{\mathrm{i}}+2\widehat{\mathrm{j}}+3\widehat{\mathrm{k}},\overrightarrow{\mathrm{b}}=3\widehat{\mathrm{i}}+\widehat{\mathrm{j}}-\widehat{\mathrm{k}}\text{ and }\overrightarrow{\mathrm{c}}$ be three vectors such that $\overrightarrow{\mathrm{c}}$ is coplanar with $\overrightarrow{\mathrm{a}}\text{ and }\overrightarrow{\mathrm{b}}$. If the vector $\overrightarrow{\mathrm{c}}$ is perpendicular to $\overrightarrow{\mathrm{b}}\text{ and }\overrightarrow{\mathrm{a}}\cdot \overrightarrow{\mathrm{c}}=5$, then $\left|\overrightarrow{\mathrm{c}}\right|$ is equal to