241 (two hundred [and] forty-one) is the natural number between 240 and 242. It is also a prime number. In mathematics 241 is the larger of the twin primes (239, 241). Twin primes are pairs of primes separated by 2. 241 is a regular prime and a lucky prime. Since 241 = 15 × 24 + 1, it is a Proth prime. 241 is a repdigit in base 15 (111). 241 is the only known Lucas–Wieferich prime to (U, V) = (3, −1). In Chemistry Americium-241 is the most common isotope of Americium, used in smoke detectors. In popular culture Reel Big Fish wrote a song entitled "241," where the number is repeated as the only lyric. Another song entitled "241" is sung by Filipino band Rivermaya. See also List of highways numbered 241 References Integers