1721
This number is a prime.
(1721-1)^4 + 1721^4 + (1721+1)^4 = 26317541869937 is prime.
1721 and 1723 are twin primes. Given product of the first
32 primes x = 2*3*...*131, it is curious that x+1721 and
x+1723 are also twin primes.
1721 and 1723 are twin primes.
The sums of their digits 1+7+2+1 and 1+7+2+3 are also twin
primes: 11, 13.
Concatenating the prime previous to 1721 with itself (17091721) is prime. [Noll]
The year Sir Robert Walpole was elected as the first British Prime Minister. [Homewood]
The smallest prime p such that the Euler's prime generating polynomial p2 + p + 41 is not squarefree. Infact, the value generated is not cubefree as well. [Gudipati]
Printed from the PrimePages <t5k.org> © G. L. Honaker and Reginald McLean