# 241 (number)

 ← 240 241 242 →
Cardinal two hundred forty-one
Ordinal 241st
(two hundred forty-first)
Factorization prime
Prime twin prime
Greek numeral ΣΜΑ´
Roman numeral CCXLI
Binary 111100012
Ternary 222213
Quaternary 33014
Quinary 14315
Senary 10416
Octal 3618
Duodecimal 18112
Vigesimal C120
Base 36 6P36

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[1] and a lucky prime.[2]

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.
• A short form of the phrase "Two for One" describing a discount.