99999...23133 (45-digits)

This number is a composite.

                           99999 9999888888 8877777776 6666655555 4444223133

The greatest semiprime composed of one 1, two 2's, ..., nine 9's. That is, 999999999888888887777777666666555554444223133/3 = 333333333296296295925925888888851851481407711 is prime. [Poo Sung]