factor has 11 distinct synonyms spread across 6 of its 10 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
anything that contributes causally to a result
“a number of factors determined the outcome”
one of two or more integers that can be exactly divided into another integer
“what are the 4 factors of 6?”
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
“genes were formerly called factors”
resolve into factors
“a quantum computer can factor the number 15”
be a contributing factor
“make things factor into a company's profitability”
consider as relevant when making a decision
“You must factor in the recent developments”
Synonyms, antonyms and the broader and narrower relations for factor come from Princeton University’s WordNet. Full sources and licences.