Yes, FACTOR is a Scrabble word!

Letter values in Scrabble US: F 4, A 1, C 3, T 1, O 1, R 1.

Is it a valid word?

FACTOR is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

anything that contributes causally to a result
an abstract part of something
one of two or more integers that can be exactly divided into another integer
a businessman who buys or sells for another in exchange for a commission
any of the numbers (or symbols) that form a product when multiplied together
an independent variable in statistics
(genetics) a segment of DNA that is involved in producing a polypeptide chain; it can include regions preceding and following the coding DNA as well as introns between the exons; it is considered a unit of heredity

Also: factor in, factor out.