29728...78401 (32-digits)

This number is a prime.

                                         29 7283071559 6370681022 8435378401

Go to Alpertron and type in the sum of 2 consecutive cubes number of (2^210)^3+(2^210+1)^3. Click Factor and wait a few seconds. Click More, type in 777, and click on New curve. As of September 16, 2020, it displays possibly the only known prime number at lucky number curve 777. [Stath]