11111...11111 (271-digits)

This number is a composite.

         1 1111111111 1111111111 1111111111 1111111111 1111111111 1111111111
1111111111 1111111111 1111111111 1111111111 1111111111 1111111111 1111111111
1111111111 1111111111 1111111111 1111111111 1111111111 1111111111 1111111111
1111111111 1111111111 1111111111 1111111111 1111111111 1111111111 1111111111

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

           1 1 1 1 1 1 1 1 1 1 
          1 1 1 1 1 1 1 1 1 1 1 
         1 1 1 1 1 1 1 1 1 1 1 1 
        1 1 1 1 1 1 1 1 1 1 1 1 1 
       1 1 1 1 1 1 1 1 1 1 1 1 1 1 
      1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
     1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
    1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
   1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
  1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
   1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
    1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
     1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
      1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
       1 1 1 1 1 1 1 1 1 1 1 1 1 1 
        1 1 1 1 1 1 1 1 1 1 1 1 1 
         1 1 1 1 1 1 1 1 1 1 1 1  
          1 1 1 1 1 1 1 1 1 1 1

A repunit hex-congruent prime in base 6. [Dobb]