6869

This number is a prime.

The smallest circular-digit prime formed by the concatenation of two consecutive multidigit numbers; when 0's are added between each number we get the smallest six-digit number with same property, 608609; then when the 60's are removed we get the smallest of all, 89. [Punches]

The only composite-digit prime concatenated in order from two successive double-digit numbers. [Loungrides]