Sum of 714 and 715

Theorem
The sum of $714$ and $715$ is a $4$-digit integer which has $6$ anagrams which are prime.

Proof
We have that:
 * $714 + 715 = 1429$

Hence we investigate its anagrams.

We bother only to check those which do not end in either $2$ or $4$, as those are even.

Of the above, $6$ are seen to be prime.