If $A=\left[a_{i j}\right]_{3 \times 3}=\left[\begin{array}{lll}3 & 2 & 4 \\ 1 & 4 & 1 \\ 2 & 6 & 3\end{array}\right]$ and $A_{i j}$ is a cofactor of $a_{i j}$, then the value of $a_{21} A_{21}+a_{22} A_{22}+a_{23} A_{23}$ is equal to