47731...64991 (15092-digits)
This number is a prime.
Just showing those entries submitted by 'Broadhurst': (Click here to show all)
 
Call this prime P. Then Q=16*P-15 and 
R=(P-1)*(16*P+1)/9266506659322630097+1
are also primes. 
As of September 2003, N=P*Q*R was the largest 
known Carmichael number with precisely 3 prime factors. 
In other words, N divides (a^N-a) for every positive
integer a.  [Broadhurst]
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