This number is a prime.
Just showing those entries submitted by 'Beiler': (Click here to show all)
91 is composite, 9901 is prime, 999001 is composite, 99990001 is prime, 9999900001 is composite, 999999000001 is prime, 99999990000001 is composite, 9999999900000001 is prime. Unfortunately, the next two terms in this sequence are each composite. [Beiler]