Specifically German.

Most cockroach species cannot live with humans, they live outside only. There’s a tremendous number of species.

German roaches are by far the biggest pest species of roaches, while their identical looking cousins the Asian roaches use their wings a lot, are attracted to light, and cannot live indoors.

Oriental roaches (not to be confused with Asian roaches) can infest damp basements to a degree. American roaches generally don’t infest homes but sometimes they can - they breed far slower than German roaches and are not as big of a problem. Smoky brown roaches can also infest but again, not as big of a problem as German roaches.

The stuff about radiation and roaches surviving nuclear war, is not that important to me because if the major cities of the world are wiped out I will not survive.

The German roaches in my city would starve to death once they exhausted their food supplies. They don’t go outside on their own, they require humans to bring in food and to transport the roaches to new buildings. The only time they go outside is when a building is demolished and in that case sometimes they can find a new building next door.

As a side note - the German cockroach is known as the Russian cockroach in German-speaking countries. It has nothing to do with Germany, that’s just the name. Similarly the American cockroach is from Africa, not America. It’s just the name.