List of recent champions for factoring Cunningham numbers: Pollard p-1: 5267 P58 2,2098M P. Zimmermann 4871 P57 6,396+ P. Zimmermann Quadratic sieve method: 4682 C135 2,1606L Dodson, A.K. Lenstra, Leyland, Muffett, Wagstaff 4564 C124 2,895- Jens Franke Special number field sieve by size of number factored: 5331 c274 6,353- Aoki+Kida+Shimoyama+Ueda 4949 c248 2,1642M Aoki+Kida+Shimoyama+Sonoda+Ueda/CRYPTREC Special number field sieve by SNFS difficulty: 5331 c274 6,353- Aoki+Kida+Shimoyama+Ueda 4949 c248 2,1642M Aoki+Kida+Shimoyama+Sonoda+Ueda/CRYPTREC Hybrid Special/General number field sieve by size of number factored: 4083 C123 2,1155+ CWI 4036 C121 2,1650L CWI General number field sieve by size of number factored: 5158 C176 11,281+ Aoki+Kida+Shimoyama+Ueda 4924 C164 2,1826L Aoki+Kida+Shimoyama+Sonoda+Ueda/CRYPTREC 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): 5331 p120*p155 6,353- Aoki+Kida+Shimoyama+Ueda 5373 p108*p136 5,349- Kruppa/Franke/Kleinjung/Bahr/CWI First five holes in each table on February 28, 2007 2,787- c204 2,799- c188 2,821- c208 2,823- c197 2,827- c172 2,779+ c212 2,787+ c169 2,799+ c172 2,823+ c229 2,851+ c214 2,1538M c208 2,1574L c156 2,1582L c162 2,1586L c156 2,1598L c171 2,772+ c215 2,776+ c180 2,788+ c219 2,824+ c193 2,832+ c228 3,523- c233 3,527- c160 3,529- c237 3,533- c202 3,539- c197 3,499+ c238 3,506+ c196 3,508+ c188 3,509+ c171 3,512+ c193 5,317- c194 5,323- c186 5,331- c187 5,341- c175 5,347- c210 5,331+ c193 5,346+ c174 5,353+ c231 5,358+ c233 5,361+ c221 6,283- c173 6,299- c155 6,305- c155 6,313- c227 6,329- c150 6,284+ c168 6,292+ c225 6,298+ c215 6,302+ c173 6,304+ c216 7,263- c161 7,269- c224 7,271- c214 7,277- c201 7,281- c165 7,268+ c185 7,277+ c165 7,281+ c193 7,293+ c187 7,296+ c190 10,239- c228 10,241- c229 10,257- c241 10,263- c216 10,269- c233 10,229+ c164 10,232+ c160 10,236+ c193 10,239+ c221 10,241+ c175 11,227- c195 11,229- c217 11,233- c181 11,239- c246 11,241- c220 11,226+ c222 11,233+ c200 11,241+ c242 11,244+ c247 11,254+ c228 12,229- c242 12,233- c215 12,239- c202 12,241- c260 12,247- c209 12,227+ c213 12,232+ c181 12,244+ c190 12,253+ c169 12,254+ c230