Verified Answer :

the community answer for this equation could be 72113 or 21713.

commutative property
abc=acb=bac=bca=cab=cba
multiplicatoin can move

some possible ones
(13)(7)(21)=(13)(21)(7)=(21)(7)(13)=(21)(13)(7)=(7)(13)(21)=(7)(21)(13)
any of those work