My Probable Prime (PRP) Records


 Type of number   Largest known probable prime factor           Digits  
 Mersenne  (2173867-1)/52536637502689  52326
 Fibonacci  U(348307)/20562890865908093  72776
 Lucas  V(277273)/11090921  57940
 Factorial -1  (14450!-1)/225296581  53829
 Factorial +1  (13224!+1)/221497  48755
 Phi(x, n!)   x = 3 to 24  Phi(7, 2210!)/68224198354698667  38584
 Primorial -1  (136777# -1)/8823581477  59254
 Primorial +1  (95617# +1)/3731593  41415
 Cullen  (98242 . 298242+1)/353047001  29571
 Woodall  (109131 . 2109131-1)/7  32856
 Repunit  ((1020233-1)/9)/2642301179019648233041  20211

 more...



Largest known cousin (probable) prime numbers
630062 . 237555 +3, +7    (11311 digits)
Note: Cousin primes are a pair of prime numbers of the form (p, p+4)



All probable prime numbers on this page have passed a Miller-Rabin primality test in 10 randomly chosen bases (ispseudoprime test in PARI/GP). All probable prime numbers on this page were found by me and are listed on Henri Lifchitz's Top 10000 PRPs page.


My FactoProth and PrimoProth records
Main page


Last updated on July 12, 2007
Donovan Johnson