ECM. The previous record was 66 digits, found by B. Dodson on April 6, 2005. The previous record was 59 digits (10233-1) found by B. Dodson on February 20, 2005. The previous record was 58 digits (8*10141-1), found by R. Backstrom on November 1st, 2003 (however with a p52 cofactor, thus it could have been found by NFS, thus this record was not taken into account in Richard Brent champions list). The previous record was 57 digits (2997-1), found by B. Dodson on 21st June 2003. The previous record was 55 digits (9356+5693) found by P. Gaudry on 13 December 2002. The previous record was 54 digits [(6^43-1)^42+1, factored by Nik Lygeros and Michel Mizony on December 26, 1999]. The previous records were: a p53 factor from 2^677-1 c150 found by Conrad Curry on September 14, 1998; a p49 factor from 2^1071+1 c132 found by Paul Zimmermann on June 19, 1998; a p48 factor from 24^121+1 c130 found by Richard P. Brent on October 9, 1997; a p47 factor from 30^109-1 c89 found by Peter Montgomery on February 25, 1996 (however from a c89, thus not taken into account in Richard Brent champions list); a p47 factor from 5^256+1 c134 found by Peter Montgomery on November 27, 1995; a p44 factor from p(19069) c99 found by Berger-Mueller on June 21, 1995; a p43 factor from p(19997) c139 found by Berger-Mueller on March 20, 1993; a p42 factor from 10^201-1 c111 found by D. Rusin on April 5, 1992; a p40 factor from p(11279) c89 found by Lenstra-Dixon on October 28, 1991 (graphical representation). See a description of the algorithm(s).
Special Numbers. The previous record was 248 digits, with 2,1642M factored by Aoki/Kida/Shimoyama/Sonoda/Ueda (CRYPTREC) on April 04, 2004. The previous record was 244 digits, with 2809-1 factored by Franke/Kleinjung/Bahr/CWI on January 3, 2003. The previous record was 233 digits for the special number field sieve or SNFS ( 2^773+1 by The Cabal in November 2000).