因数 is read as いんすう (insuu) and means factor.
いんすう
insuu
いんすうていり
factor theorem
いんすうぶんかい
factorization
きょうつういんすう
common factor
ぶろっくかいんすう
blocking factor
そいんすう
prime factor
そいんすうぶんかい
prime factorization
いん
hetu (direct cause, esp. as opposed to indirect conditions)
いんし
factor
いんが
cause and effect
いんしゅう
convention
ちなみに
by the way
いんししゅうごう
factor set