List of recent champions for factoring Cunningham numbers: Pollard p-1: 5267 P58 2,2098M P. Zimmermann 4871 P57 6,396+ P. Zimmermann Special number field sieve by size of number factored: 5501 c307 2,1039- K.Aoki+J.Franke+T.Kleinjung+A.K.Lenstra+D.A.Osvik 5331 c274 6,353- Aoki+Kida+Shimoyama+Ueda Special number field sieve by SNFS difficulty: 5501 c307 2,1039- K.Aoki+J.Franke+T.Kleinjung+A.K.Lenstra+D.A.Osvik 5739 c228 12,256+ T.Womack+B.Dodson 5331 c274 6,353- Aoki+Kida+Shimoyama+Ueda General number field sieve by size of number factored: 5723 C182 2,1157- J.Bos+T.Kleinjung 5667 C180 5,421- Mersenneforum+Womack Elliptic curve method: 5418 P67 10,381+ B. Dodson ECMNET 5135 P66 3,466+ B. Dodson ECMNET Largest penultimate prime factor (ultimate factor shown also): 5714 p128*p140 5,383+ Childers/Dodson 5654 p127*p136 6,392+ Childers/Dodson First five holes in each table on October 9, 2009 2,863- c234 2,887- c210 2,899- c185 2,913- c233 2,919- c261 2,851+ c214 2,853+ c221 2,859+ c233 2,881+ c190 2,887+ c207 2,1646L c208 2,1654L c195 2,1678L c197 2,1678M c197 2,1706M c244 2,856+ c223 2,904+ c210 2,932+ c200 2,956+ c187 2,964+ c198 3,551- c238 3,563- c199 3,569- c231 3,589- c213 3,593- c214 3,538+ c177 3,548+ c197 3,559+ c225 3,562+ c255 3,563+ c239 5,361- c189 5,383- c183 5,389- c231 5,391- c161 5,397+ c258 5,361+ c221 5,373+ c214 5,377+ c171 5,382+ c172 5,386+ c223 6,349- c209 6,355- c206 6,365- c185 6,371- c217 6,373- c287 6,323+ c221 6,331+ c227 6,332+ c177 6,334+ c239 6,335+ c162 7,311- c225 7,323- c241 7,335- c219 7,337- c213 7,353- c263 7,293+ c187 7,304+ c244 7,307+ c225 7,314+ c215 7,320+ c201 10,269- c233 10,271- c214 10,277- c224 10,281- c210 10,283- c211 10,244+ c215 10,248+ c199 10,268+ c243 10,272+ c212 10,274+ c253 11,229- c217 11,233- c181 11,241- c220 11,257- c226 11,263- c209 11,254+ c228 11,263+ c252 11,269+ c202 11,271+ c267 11,272+ c201 12,233- c215 12,239- c202 12,247- c209 12,257- c218 12,269- c205 12,232+ c181 12,254+ c230 12,265+ c185 12,266+ c179 12,271+ c250