Well out of the 118 commissioned Type XXIs built between 1943 and 1945, U-3515, U-3514, U-3041, U-3035, U-3017, U-2518, U-2513, U-2511, U-2506, and U-2502 surrendered in Norwegian ports at the end of the war. A large number of these U-Boats where scuttled at Travemünde on the 2-3rd of May 1945. Of the 10 Type XXI U-Boats that surrendered in Norway the U-2502 was selected for testing by the Royal Navy and was later sunk during Operation Deadlight. U-2513 was secretly transferred to the United States Navy and was sunk during rocket trials on 7 October 1951 off Key West, Florida. U-2518 became part of the French Navy and renamed "Roland Morillot", was stricken 17 October 1967 and was broken up in 1969. U-2529, U-3035, U-3041, and U-3515 where allocated to the Soviet Navy by the TNC. U-2017 became Royal Navy submarine N 41, broken up Newport, Wales November 1949. U-2506, U-2511, and U-3514 where sunk as part of Operation Deadlight. Got all the info from Uboat.net. Link here:
https://uboat.net/types/xxi.htm