1871

This number is a prime.

The German Empire was founded in 1871. Additionally, the product of its digits plus the sum of its digits is prime! 1871 also forms a twin prime pair, i.e. (1871, 1873), and the sum of digits of 1871 is prime and the sum of digits of 1873 is also prime - therefore, forming yet another twin prime pair. [Anitha]