
Curios:
Curios Search:
Participate: 
444444444 is the only ninedigit repunit such that the product of itself and all truncations of itself minus one is prime. I.e., 444444444*44444444*4444444*444444*44444*4444*444*44*4  1 is prime. There are no such tendigit repunits. [Opao]
Prime Curios! © 20002014 (all rights
reserved)
