The ATPL requires a minimum of 1500 hours, which must include:
500 hrs multi-pilot in transport or commuter aircraft
250 hrs PIC (or 100 PIC and 150 PICUS)*
200 hrs cross country flights (100 as PIC or PICUS)
75 hrs instrument time
100 hrs night flight as PIC or co-pilot
* PIC is Pilot-In-Command and PICUS is Pilot-In-Command-Under-Supervision
If you have sat the ATPL groundschool examinations succesfully, but not achieved the hour requirements for the ATPL licence then this is referred to as a frozen ATPL. Normally, the holder will be a CPL/IR ME with the ATPL groundschool exams under their belt.