aparteni

Aparteni is intransitive and always takes al. The owner is never a direct object, so tio apartenas al mi and never tio apartenas min. That makes it the mirror image of havi: mi havas la libron and la libro apartenas al mi say the same thing from the two ends. It covers membership as readily as ownership, which is how you say you belong to a club or a nation. For the sense of a thing being in its proper place, Esperanto prefers esti en sia loko. The related apartenaĵo is a belonging or an appurtenance.