Number Gossip

(Enter a number and I'll tell you everything you wanted to know about it but were afraid to ask.)

Unique Properties of 3

3 is the greatest number of consecutive integers that can be pairwise relatively prime
3 is the only prime sandwiched between a prime and a composite number
3 is the only prime followed by a square
Every positive integer is the sum of at most 3 triangular numbers
If the n-th Fibonacci number is prime, then n must itself be prime, with the exception of 3, which is the 4th Fibonacci number
3 is the only number which is equal to the sum of all the natural numbers less than it
3 is the only triangular number that is also prime
the only twin prime triplet starts at 3
is the first odd prime number
3 is the smallest evil number
3 is the only integer between e and pi