The word factorises is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 16
Highest Scoring Words With Friends™ Plays In The Letters factorises
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Seven Letter Word Alert: (37 words)
actress, ascites, casters, castors, coaster, corsets, cosiest, costars, cristae, erotica, erotics, escorts, factors, fairest, fascist, fiestas, foister, forests, forties, fosters, frescos, oecists, raciest, racists, recasts, recoats, resifts, rosiest, satires, scoriae, scorias, sectors, sifters, softies, sorties, stories, strifes