323

This number is a composite.

The smallest palindrome whose factors are twin primes (17 * 19). [Russo]

323 doubled up (i.e., 323323) has five consecutive prime factors which when squared and summed, yield 989, another palindrome! [De Geest]

323 is the smallest Lucas pseudoprime. [Terr]

The smallest brilliant Honaker number. [Gaydos]

The smallest composite number n which divides the (n+1)^th Fibonacci number. Such Fibonacci pseudoprimes are proven to be infinite. [Gudipati]