Converting Last Agent Scan to Date/Time - SQL

Converting Last Agent Scan to Date/Time - SQL

I have tried all of these and the last scan date shows as 1970... what am i doing wrong?

SELECT [WORKSTATIONID],
[LASTAGENTSCANTIME],
DATEADD(ms, ServiceDesk.dbo.SystemInfo.LASTAGENTSCANTIME / 86400000, ServiceDesk.dbo.SystemInfo.LASTAGENTSCANTIME / 86400000 + 25567),

convert(datetime2,convert(datetime,(LASTAGENTSCANTIME /86400000)+25567)),

DATEADD(MILLISECOND, LASTAGENTSCANTIME % 1000, DATEADD(SECOND, LASTAGENTSCANTIME / 1000, '19700101')),

dateadd(s,datediff(s,GETUTCDATE() ,getdate()) + (ServiceDesk.dbo.SystemInfo.LASTAGENTSCANTIME/1000),'1970-01-01 00:00:00')

FROM [dbo].[SystemInfo]

this is the results:
2401 1730825181 1970-01-21 00:00:00.020 1970-01-21 00:00:00.0000000 1970-01-21 00:47:05.180 1970-01-20 18:47:05.000

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