I call it odd.
I would call an odd number factor a factor that is an odd number. I would call a number with an odd number of factors a perfect square.
I call it 1.
A Factor
when it goes into another number
I think that might be better phrased as a number with two factors. That's a prime number.
It is called a common factor!
factor a^2-b^2
It is a factor of the number to be divided
prime number
One.
I call them odd.
It's easy to see whether 2 is a factor of a number because 2 is a factor of every even number and not a factor of any odd number.