Earlier quoted context omitted.
If by "this" you mean the 83-digit prime in the question, then no. There's no indication that there are no other 83-digit bitruncatable primes - that's just the only one the author had found. If you mean the sole 97-digit solution given in the comments, the implication that all the bitruncatable primes have been found and enumerated by your method, and the assertion that there are no such 99-digit primes - then yes,…
> I'd want to see an independent verification I wrote a solver for this problem: https://github.com/jwilk/bitruncatable-primes I haven't run it yet, because I don't have a powerful-enough machine at hand. It needs ~6 GB of RAM and ~20 CPU core-hours.
7228828176786792552781668926755667258635743361825711373791931117197999133917737137399993737111177 (97 digits)
is indeed the biggest bi-truncatable prime.
This was done under assumption that zero digits are not allowed. If they are allowed, bigger bi-truncatable primes exists, such as:
90072457733413689120801410250233316614403998951220231333193991731791997911317971131797197339199333933 (101 digits)