Samuel Yates began, and this site continues, a database of the largest known primes. Primes in that database are assigned a proof-code to show who should be credited with the discovery as well as what programs and projects they used. (Discoverers have one prover-entry, but may have many proof-codes because they use a variety of programs...)
This page provides data on L1721, one of those codes.
Code name (*): L1721 Persons (*): 1 (counting humans only) Projects (*): 1 (counting projects only) Display (HTML): Spencer, TwinGen, PrimeGrid, LLR Number of primes: total 1 Unverified Primes: 0 (prime table entries marked 'Composite','Untested', or 'InProcess' Score for Primes (*): total 41.6991
Below is additional information about this entry.
Display (text): Spencer, TwinGen, PrimeGrid, LLR Display (short): Spencer Database id: 5125 (do not use this database id, it is subject to change) Proof program: LLR Entry last modified: 2023-12-07 22:37:16