What is cincuenta y uno?

Cincuenta y uno is the Spanish phrase for the number fifty-one in English. It is an odd prime number that comes after fifty and before fifty-two. It is represented in Roman numerals as LI, and in binary as 110011. In common usage, it is often used as a reference to a chronological or numerical sequence of events, where fifty-one would follow the fiftieth event or instance. Additionally, the phrase "cincuenta y uno" is often used colloquially to refer to a person who is over fifty years old but still active and youthful.