|Cardinal||two hundred forty-one|
(two hundred forty-first)
241 (two hundred [and] forty-one) is the natural number between 240 and 242. It is also a prime number.
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).
Americium-241 is the most common isotope of Americium, used in smoke detectors.