What is the int.MaxValue on a 64-bit PC?

Yes, the answer will be the same on a 64-bit machine.

In .NET, an int is a signed 32-bit integer, regardless of the processor. Its .NET framework type is System.Int32.

The C# Language specification states:

The int type represents signed 32-bit
integers with values between
–2,147,483,648 and 2,147,483,647.