What Is A 64-bit Integer?

What Is A 64-bit Integer? Int64 is an immutable value type that represents signed integers with values that range from negative 9,223,372,036,854,775,808 (which is represented by the Int64. … NET Framework also includes an unsigned 64-bit integer value type, UInt64, which represents values that range from 0 to 18,446,744,073,709,551,615. How big is a 64-bit int?