66666...66667 (1204-digits)

This number is a probable-prime (likely to be a prime but we have not (re-)proven it on this site).

Just showing those entries submitted by 'Rivera': (Click here to show all)

6_n 7 is prime for n=1203. Its square, 4_n+1 8_n 9, is an integer of 2408 digits, free of the digits 6 and 7. [Rivera]