...Nach langen herumprobieren hab ich es mal mit "Format" probiert und siehe dar "Format('%u',[UInt64(-1)])" liefert die gewünschten "18446744073709551615"
http://www.delphibasics.co.uk/NameSp...em&Part=UInt64
Description
The UInt64 structure holds positive integer values from 0 to 18,446,744,073,709,551,615.
Note that when converting to Hexadecimal, xFFFFFFFFFFFFFFFF for UInt64 means 18,446,744,073,709,551,615. , but for Int64 it means -1.
Methods
CompareTo Compares the current UInt64 value to another
Equals Determines if the current UInt64 equals another
Parse Converts a string representation of a UInt64 into a UInt64 value
ToString Converts the current UInt64 value to a string
Fields
MinValue Integer Smallest possible value : 0 (0x0000000000000000 in hex)
MaxValue Integer Largest possible value : 18,446,744,073,709,551,615 (0xFFFFFFFFFFFFFFFF in hex)