Rindfleischetikettierungsüberwachungsaufgabenübertragungsgesetz -
63 words long - a law describing the regulation of beef labeling! Considered satirical even by native German speakers.
Since repealed.
I think you mean "63 letters long."
In Switzerland, they say their roughest word to pronounce, with the extra guttural ch, is chöchichastli (kitchen cupboard) but that’s not it. The hardest one is chäschüechli because the first two vowels are Especally hard as well. A chäschüechli is a little hot savory cheese pie, bought from vendors on the street, delicious on a cold day.