Interesting here and in some of the other comments in this thread is that 1 is not a prime number ¹)!
Now granted, that's more or less by definition and I don't doubt there's communities and fields where it is considered one, but still shows some of the subtleties at play when using language models.
Whether 1 should be a prime number or not wasn't clear-cut for centuries.
Current consensus has settled on excluding 1 from the definition, but there are examples of publications well into the 20th century that still included 1 as prime.
