823

This number is a prime.

Victor Hugo's Les Misérables contains one of the longest sentences (823 words without a period) in the French language.

The "823-year" claim is a myth. [Kher]

823 = 12345/(1+2+3+4+5). The only known prime with this property. [Capelle]

The first of nine consecutive primes that are all Yarborough primes. [Gaydos]

The larger of only two 3-digit primes p, such that its square p^2 is a concatenation of three double-digit primes, i.e., 823^2 = 677329. [Loungrides]