I ran across this link on cognitive psychology regarding a study that finds that 17 is the most random number. Or at least that is what people most often choose when they are picking a random number between 1 and 20. It’s an interesting study (I’ve heard of this before but never in quite this way).
The reason this is interesting is not just related to a random number, but in picking passwords, secret questions or any other “what you know” type security mechanisms in applications. It’s also true that people tend to pick prime numbers more often than computers when asked to create a random number. Apparently people tend to think of randomness as being associated with being indivisible by 2.
In direct opposition it appears that the number 20 is the least random number, in that the fewest people picked it (sounds backwards because it is). It’s an interesting study anyway.