Int64
From Xojo Documentation
Data Type
Used to store 64-bit integer values. The default value is 0. Generally you will use the Integer data type (equivalent to Int32 on 32-bit apps or Int64 on 64-bit apps) or UInteger (equivalent to UInt32 on 32-bit apps or UInt64 on 64-bit apps). This size-specific integer data type is available for use with external OS APIs.
Notes
Int64 values can range from -2^63 to 2^63-1 (-9,223,372,036,854,775,808 to +9,223,372,036,854,775,807) and use 8 bytes.