# 241

This number is a prime.

The second unique prime in hexadecimal (base 16).

The prime numbers are identified as N0241 in Sloane's original "Handbook of Integer Sequences."

The smallest prime *p* such that *p* plus the reversal of *p* equals a palindromic prime. [Luhn]

Internationally renowned researcher Dr. Karen Rogers did a study of 241 profoundly gifted children in 1994-1995 during a postdoctoral fellowship. It was especially useful to parents who had observed developmental differences in their children but were unaware of what those differences may signify.

The smallest duodecimal prime: p = (x^12 + y^12 )/(x^4 + y^4 ). [Russo]

The smallest non-palindromic prime which can be expressed as sum of a number and its reverse, i.e., 241 = 170 + 071. [Gupta]

The system of equations: 2w + 3x + 5y + 7z = 11; 13w + 17x + 19y + 23z = 29; 31w + 37x + 41y + 43z = 47; 53w + 59x + 61y + 67z = 71; has four fractions as its solution, each of which has denominator 241. [Rupinski]

The smallest prime p such that the concatenation of p in base 10 down up to base 2 is prime. [Russo]

The smallest prime *p* such that *p*^{7} can be written as the sum of 7 consecutive primes. Note that 2 + 4 + 1 = 7. [Rivera]

The radioisotope americium-241 is used in many smoke detectors.

The smallest prime value (out of 14) resulting from the ninedigital fraction equation (A/B)^C + (D/E)^F + (G/H)^I, where the letters A to I represent any combination of the nine digits 1 through 9. Note that (6/3)^5 + (8/4)^7 + (9/1)^2 and (6/3)^7 + (8/4)^5 + (9/1)^2 are the only two distinct solutions for 241. [De Geest]

241 is the only number m such that prime(m) = π(m * π(m)). [Firoozbakht]

The United States Supreme Court case Chesapeake & Ohio Railway Company v. Asa P. Carnahan can be found on Page 241 of Volume 241.

This easy-to-remember member of a twin prime pair is pronounced, "two for one." Get it?

241 = prime(prime(2!!*4!!*1!!)). [Javadifar]

There are 241 known numbers that cannot be written as the sum of at most four tetrahedral numbers. [Capelle]

The largest known prime p such that the reversal of (p! + p) is prime. [Firoozbakht]

Washington D.C. schools chancellor Michelle Rhee once fired 241 teachers at the same time.

If A = 1, B = 2, C = 3, ... , Z = 26, then 'THE RIEMANN HYPOTHESIS' is prime. [Homewood]

The largest prime that can be represented as sum of three double-digit emirps, i.e., 71+73+97=241. [Loungrides]

Let U(0) = 0, U(1) = 1, U(n) = 3*U(n-1) + U(n-2) for n>1, then 241 is the only known prime p such that p^2 divides U(p-(13|p)), where (13|p) is the Legendre symbol, i.e., a Wall-Sun-Sun-type prime to this Lucas sequence. [Luen]

241 is the only known Lucas–Wieferich prime to (U, V) = (3, −1). [Lemmett]

241 = (22^2-2)/2. Can you find the next prime of form (*t*^2-2)/2, where *t* is a repdigit of form 2*(10^n-1)/9? [Honaker]

During the Terror, the Military Commission presided over by Lenoir sentenced 241 people to death. Reference: Alfred Lallié (1896) La justice révolutionnaire à Nantes et dans la Loire-Inférieure. Nantes, B. Cier, p. xxvii. [Olry]

North America's highest mountain (Denali) is 241 feet lower than Mount Chimborazo. [Green]

241 athletes participated in the first international Olympic Games held in modern history. [Orr]

The prime counting function π(241) = 53 uses the distinct-digit set {1, 2, 3, 4, 5} only, and 241 is the smallest prime with this property. Note that π(53) = 2^4*1. [Worrom]