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
prime number
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.
One.
If 2 is a factor, the number is even.
In order to determine if 2 is a factor of 49 (or any other number), ask yourself if the number is even or odd. If the number is odd, it is not a factor of 2. 49 is odd, so 2 is not a factor of 49. You can also divide 2 into the number. If there is no remainder, 2 is a factor of the number. 49 divided by 2 is 24 with a remainder of 1, so 2 is not a factor of 49.