1) Incapable of being decomposed 
Indecomposable has multiple meanings in the field of mathematics: ...
• (a.) Not decomposable; incapable or difficult of decomposition; not resolvable into its constituents or elements.
In·de`com·pos'a·ble adjective [ Prefix in- not + decomposable : confer French indécomposable .] Not decomposable; incapable or difficult of decomposition; not resolvable into its constituents or elements. 
incapable of being decomposed.