Prime Numbers

A prime number has only two different factors. They are 1 and the number itself. 13 is a prime number because the only factors of 13 are 1 and 13. Note that 1 is not a prime number.


The following table lists all odd numbers from 3 to 991 and if the number is not a prime the lowest factor is given.

3
Prime
5
Prime
7
Prime
9
3
11
Prime
13
Prime
15
3
17
Prime
19
Prime
21
3
23
Prime
25
5
27
3
29
Prime
31
Prime
33
3
35
5
37
Prime
39
3
41
Prime
43
Prime
45
3
47
Prime
49
7
51
3
53
Prime
55
5
57
3
59
Prime
61
Prime
63
3
65
5
67
Prime
69
3
71
Prime
73
Prime
75
3
77
7
79
Prime
81
3
83
Prime
85
5
87
3
89
Prime
91
7
93
3
95
5
97
Prime
99
3
101
Prime
103
Prime
105
3
107
Prime
109
Prime
111
3
113
Prime
115
5
117
3
119
7
121
11
123
3
125
5
127
Prime
129
3
131
Prime
133
7
135
3
137
Prime
139
Prime
141
3
143
11
145
5
147
3
149
Prime
151
Prime
153
3
155
5
157
Prime
159
3
161
7
163
Prime
165
3
167
Prime
169
13
171
3
173
Prime
175
5
177
3
179
Prime
181
Prime
183
3
185
5
187
11
189
3
191
Prime
193
Prime
195
3
197
Prime
199
Prime
201
3
203
7
205
5
207
3
209
11
211
Prime
213
3
215
5
217
7
219
3
221
13
223
Prime
225
3
227
Prime
229
Prime
231
3
233
Prime
235
5
237
3
239
Prime
241
Prime
243
3
245
5
247
13
249
3
251
Prime
253
11
255
3
257
Prime
259
7
261
3
263
Prime
265
5
267
3
269
Prime
271
Prime
273
3
275
5
277
Prime
279
3
281
Prime
283
Prime
285
3
287
7
289
17
291
3
293
Prime
295
5
297
3
299
13
301
7
303
3
305
5
307
Prime
309
3
311
Prime
313
Prime
315
3
317
Prime
319
11
321
3
323
17
325
5
327
3
329
7
331
Prime
333
3
335
5
337
Prime
339
3
341
11
343
7
345
3
347
Prime
349
Prime
351
3
353
Prime
355
5
357
3
359
Prime
361
19
363
3
365
5
367
Prime
369
3
371
7
373
Prime
375
3
377
13
379
Prime
381
3
383
Prime
385
5
387
3
389
Prime
391
17
393
3
395
5
397
Prime
399
3
401
Prime
403
13
405
3
407
11
409
Prime
411
3
413
7
415
5
417
3
419
Prime
421
Prime
423
3
425
5
427
7
429
3
431
Prime
433
Prime
435
3
437
19
439
Prime
441
3
443
Prime
445
5
447
3
449
Prime
451
11
453
3
455
5
457
Prime
459
3
461
Prime
463
Prime
465
3
467
Prime
469
7
471
3
473
11
475
5
477
3
479
Prime
481
13
483
3
485
5
487
Prime
489
3
491
Prime
493
17
495
3
497
7
499
Prime
501
3
503
Prime
505
5
507
3
509
Prime
511
7
513
3
515
5
517
11
519
3
521
Prime
523
Prime
525
3
527
17
529
23
531
3
533
13
535
5
537
3
539
7
541
Prime
543
3
545
5
547
Prime
549
3
551
19
553
7
555
3
557
Prime
559
13
561
3
563
Prime
565
5
567
3
569
Prime
571
Prime
573
3
575
5
577
Prime
579
3
581
7
583
11
585
3
587
Prime
589
19
591
3
593
Prime
595
5
597
3
599
Prime
601
Prime
603
3
605
5
607
Prime
609
3
611
13
613
Prime
615
3
617
Prime
619
Prime
621
3
623
7
625
5
627
3
629
17
631
Prime
633
3
635
5
637
7
639
3
641
Prime
643
Prime
645
3
647
Prime
649
11
651
3
653
Prime
655
5
657
3
659
Prime
661
Prime
663
3
665
5
667
23
669
3
671
11
673
Prime
675
3
677
Prime
679
7
681
3
683
Prime
685
5
687
3
689
13
691
Prime
693
3
695
5
697
17
699
3
701
Prime
703
19
705
3
707
7
709
Prime
711
3
713
23
715
5
717
3
719
Prime
721
7
723
3
725
5
727
Prime
729
3
731
17
733
Prime
735
3
737
11
739
Prime
741
3
743
Prime
745
5
747
3
749
7
751
Prime
753
3
755
5
757
Prime
759
3
761
Prime
763
7
765
3
767
13
769
Prime
771
3
773
Prime
775
5
777
3
779
19
781
11
783
3
785
5
787
Prime
789
3
791
7
793
13
795
3
797
Prime
799
17
801
3
803
11
805
5
807
3
809
Prime
811
Prime
813
3
815
5
817
19
819
3
821
Prime
823
Prime
825
3
827
Prime
829
Prime
831
3
833
7
835
5
837
3
839
Prime
841
29
843
3
845
5
847
7
849
3
851
23
853
Prime
855
3
857
Prime
859
Prime
861
3
863
Prime
865
5
867
3
869
11
871
13
873
3
875
5
877
Prime
879
3
881
Prime
883
Prime
885
3
887
Prime
889
7
891
3
893
19
895
5
897
3
899
29
901
17
903
3
905
5
907
Prime
909
3
911
Prime
913
11
915
3
917
7
919
Prime
921
3
923
13
925
5
927
3
929
Prime
931
7
933
3
935
5
937
Prime
939
3
941
Prime
943
23
945
3
947
Prime
949
13
951
3
953
Prime
955
5
957
3
959
7
961
31
963
3
965
5
967
Prime
969
3
971
Prime
973
7
975
3
977
Prime
979
11
981
3
983
Prime
985
5
987
3
989
23
991
Prime

See also: Composite Number, Eratosthenes, Mersenne Prime, Relatively Prime, Sieve of Eratosthenes, Twin Primes.

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Subjects: Mathematics