long hex to long and division into number

[saduga]

hello everything, at me is hex value and I need to divide it on 512.
in a python everything is very simple, but on C# it is impossible.
hex: 0x00000000FFFF0 000000000000000 000000000000000 000000000000000 000000
in a python it turns out:
210621369461025 855415284971443 156182312585146 395110656922951 352320
Help please.
Excuse for my English.