1021

This number is a prime.

The smallest term in the only case of four emirps, (1021, 3023, 7027, 9029), formed by inserting the same 2-digit number ab, between the digits of a 2-digit repdigit number dd, where d is each of the ending digits of a multi-digit prime, i.e., inserting 02 between the digits of 11, 33, 77, 99. [Loungrides]