99999...64849 (101-digits)

This number is a prime.

                                          9 9999999999 9999999999 9999999999
9999999999 9999999999 9999999999 9999999999 9999999999 9999999999 9999964849

The largest 101-digit prime that uses all the composite digits. Note that it ends with a five digit prime, i.e., 64849. [Bajpai]