It is well-known that an inverse monoid is factorizable if and only if it is a homomorphic
image of a semidirect product of a semilattice (with identity) by a group.
We use this structure to describe a presentation of an arbitrary factorizable inverse
monoid in terms of presentations of its group of units and semilattice of idempotents,
together with some other data. We apply this theory to quickly deduce a well known
presentation of the symmetric inverse monoid on a nite set
