14285...57143 (84-digits)

This number is a prime.

                                                             1428 5715714285
7142856999 9999857142 8571428585 7142857142 8557142855 7142857142 8572857143

The smallest (and only known) unique prime [reciprocal has period 294] to contain the digits 2 and 4.

Phi(294,10)/7 is the smallest (and only known) zeroless pandigital unique prime. [Chandler]