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A rare prime of the form 2^{p} + 3, where p is prime. [Luhn] The 32nd prime. Note that 1 + 3 + 1 = 3 + 2. The least integer such that the sum of its digits in every base B = 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 is prime. [Crespi de Valldaura] Locomotive number 131 plunges off the edge of a ravine in the scifi movie Back to the Future Part III. The smallest mountain prime. [Pol] The sum of 2 + 3 + 4 + ... + 19 minus the sum of primes less than 19. [Trotter] The minimum prime p such that p + 1 each has exactly 3 distinct prime factors. [Das] Iodine131 is a radioactive isotope used in thyroid disease diagnosis and therapy. [Barnhart] The 131st Fibonacci number (1066340417491710595814572169) is the smallest Fibonacci prime which contains all the digits from 0 to 9. [Wu] The smallest multidigit palindromic prime that yields another prime by placing a 7 on both sides (as leading and trailing digits). [Russo] The sum of three twodigit primes (31 + 41 + 59) whose concatenation is the decimal expansion of . [Silva] (2! + 1) + (3! + 1) + (5! + 1) = 131. This is equivalent to 3 + 7 + 11^2. [La Haye] 131 is the smallest prime number which is sum of primes that begin with the digit 4. Note that 41, 43 and 47 are consecutive primes. [Capelle] The smallest palindromic prime with three primes embedded in it (13, 3 and 31) [Necula] The nematode Caenorhabditis elegans hermaphrodite has exactly 131 cells that are eliminated by programmed cell death (apoptosis). [Haga] The smallest palindromic super2 number, i.e., an integer n such that 2n^2 contains 2 consecutive 2s in its decimal representation. [De Geest] The sum of the first 131 nonprimes is prime. [Patterson] 131 = (1^0+3^0+1^0) + (1^1+3^1+1^1) + (1^2+3^2+1^2) + (1^3+3^3+1^3) + (1^4+3^4+1^4). Note that the summands are all primes. [Silva] 131 and the next prime after it are the first pair of consecutive primes where we can find another pair of consecutive primes by concatenating each term's end digits. [Silva] The smallest prime number appearing after the concatenation of the two preceding prime numbers (113 and 127). [Capelle] The smallest palindromic prime that yields another if the sum of digits of its consecutive digits is sandwiched between each of the corresponding consecutive digits (i.e., 131 becomes 14341). [Silva] A prime Ulam number that is the sum of two consecutive Ulam numbers (62 + 69 = 131). Can you find a greater prime example? The smallest prime that is not a quiteprime. [Beedassy] The largest prime factor of the number of mountain primes (2620 = 2^2 * 5 * 131). The smallest palindromic prime using two distinct digits which when interchanged forms another palindromic prime (313). Note that in both cases a new palindromic prime with a prime number of digits is generated when each digit d is repeated d times: 13331; 3331333. [Beedassy] The smallest prime that remains prime when the end digits (on both sides) are repeated once (i.e., 11311 is also prime). The smallest Honaker prime, i.e., 131 = P_{32}, and 1 + 3 + 1 = 3 + 2. Note that the latter sum of digits corresponds to the smallest prime with prime subscript (3 = P_{2}) added to its very (prime) subscript. [Beedassy] 131 Main is a restaurant chain in North Carolina. We recommend their slow roasted prime rib. 131 families of Coleoptera (beetles) have been described in North America. [Bartlett] The smallest prime formed from overlapping an emirp pair (13 and 31). The smallest concave prime. [Pol] 131 Calendar Club game stores were opened in 1999. A checking method is described to see if 131 is prime at the bottom of "Prime Factors" (a page from a Houghton Mifflin Harcourt website called Education Place). The smallest prime equidistant between two consecutive emirps: 113, 149. [Beedassy] The 1st prime after p(31) is 131. [Silva] The only palindromic prime that is the sum of the reversals of two doubledigit primes, i.e., 43 and 79. [Loungrides] The statue of Genghis Khan near Ulan Bator, Mongolia, is 131foot tall. The smallest 3digit prime that remains prime when inserting one, two or three zeros between its digits, i.e., 10301, 1003001, 100030001 are primes. The other is 577. [Loungrides] The smallest palindromic prime equal to a prime plus the sum of all previous composite numbers, i.e., 19+18+16+15+14+12+10+9+8+6+4. [Silva] The smallest palindromic prime that is the sum of three consecutive primes (41+43+47). [Silva] The smallest prime of form p*q(r+s), where p, q, r, s are four consecutive primes, i.e., (13, 11, 7, 5). [Loungrides] The fifth prime whose sum of digits is 5. [Loungrides] In the James Bond movie "A View to a Kill," the check that Zorin writes for S. Sutton (for $5,000,000) is numbered 131. Smallest irregular SophieGerman prime. 131 is the smallest pallindromic prime that remains so by inserting the following same digit d six times between its adjacent digits, one at a time, for d = 0, 1, 3, 4, 6, 9 (6 times): 10301 = prime 11311 = prime 13331 = prime 14341 = prime 16361 = prime 19391 = prime. [Rivera] The sum of the first one hundred thirty one 131digit primes is prime. Can you find a larger example like this? [Gaydos] Not only is 131 the first Honaker prime, but it's also a Sophie Germain prime whose associated safe prime is 263, the second Honaker prime. [Gaydos]
(There are 14 curios for this number that have not yet been approved by an editor.)
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