1871

This number is a prime.

1871 is the smallest prime factor of (3^17-1)/2.

The Paris Commune of 1871 was the first attempt at a socialist society.

1871!/1781! - 1 is prime. [Patterson]

The great Chicago fire erupted in 1871. [Green]

"Dr. Livingstone, I presume?" said H. Stanley when he located the explorer and missionary in Africa near Lake Tanganyika in 1871. [Green]

The least prime p congruent to 11 mod 12 such that (p-1)/2 does not divide the numerator of the Bernoulli number B(p-1). [Wesolowski]

Portmanteau words like repdigit (from repeated and digit) can be traced to Lewis Carrol's fantasy 1871 novel Through the Looking-Glass. After all, he was quite a mathlete.

1871 can be expressed as n-th Golden rectangle number plus one, (case n=9). [Jha]

"Whistler's Mother" was painted in 1871. [Quinley]

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]