3. In the equation $A \times B \times \overline{B B C}=\overline{A D A A}$, the same letters represent the same digits, different letters represent different digits, and $D$ is the smallest natural number, $A$ is the smallest prime number. Using the digits $A$, $B$, and $C$ to form natural numbers without repeated digits, the number of prime numbers formed is $\qquad$.
$6$