77772...27777 (121-digits)

This number is a prime.

7 7772772277 7777232777 7772222332 2227723335 3332772355
5532772352 5327723555 5327723335 3332772222 3322227777 7723277777 7227727777


               7
              7 7
             7 2 7
            7 2 2 7
   7 7 7 7 7 2 3 2 7 7 7 7 7
    7 2 2 2 2 3 3 2 2 2 2 7
     7 2 3 3 3 5 3 3 3 2 7
      7 2 3 5 5 5 5 3 2 7
       7 2 3 5 2 5 3 2 7
      7 2 3 5 5 5 5 3 2 7
     7 2 3 3 3 5 3 3 3 2 7
    7 2 2 2 2 3 3 2 2 2 2 7
   7 7 7 7 7 2 3 2 7 7 7 7 7
            7 2 2 7
             7 2 7
              7 7
               7

The smallest star-congruent prime containing all four prime digits. [Hartley]