Get id of nonexistent object for tests - django

I'm using DjangoModelFactory to create custom objects needed for tests. The issue is that I would like to write test for situation where there is a request for nonexistent object. Is there any elegant way to automatically generate such ID. One idea I have had was to use really big number, as test suite should never reach such number. Another idea is to create object, store ID and then delete the object. Both those solutions are somewhat hacky - firs has rather risky assumption that the big number will not be assigned as ID as part of tests, the other is based on additional logic which makes tests more dependent on non-related logic. Is there any simple and out-of-the box solution to get id which is not assigned to any object?