11111...11111 (25-digits)

This number is a prime.

                                                 11111 1111000100 0111111111

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

A palindromic prime taking the form of a lozenge:

         1 
        111 
       11111 
      0001000 
       11111 
        111 
         1