11111...11111 (73-digits)

This number is a composite.

                                                                         111
1111111111 1111111111 1111111111 1111111111 1111111111 1111111111 1111111111

  

             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 star-congruent prime in base 11. [Dobb]