The book is now available! 431
(another Prime Pages' Curiosity)
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+ Divide the prime number 431 by 510 to obtain an excellent approximation to log10(7). [Kulsha]

+ In addition to 431 and 433 being twin primes, both the 431st and the 433rd Fibonacci numbers are prime. [Dobb]

+ Polaris (the North Star) was thought to be about 431 light-years from Earth according to astrometric measurements of the Hipparcos satellite. It is now known to be much closer.

+ n! is divisible by the sum of the decimal digits of n! for all numbers n from 1 to 431. Note that 431 is prime also. [Gupta]

+ 2*3*5*...*prime(431-1) = prime(431)-1 (mod prime(431)). Note that 431 is the largest known prime with this property and there exist only one other known such prime. [Firoozbakht]

+ The smallest prime of form 2^n-n^2 for n a composite number. [Loungrides]

+ 431 is the only 3-digit prime number that is an anagram of the first 3 digits of pi (3.14). [Jacobs]

+ The Council of Ephesus convened near present-day Sel├žuk in 431.

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