A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 7591220 can be evenly divided by 1 2 4 5 7 10 13 14 20 26 28 35 43 52 65 70 86 91 97 130 140 172 182 194 215 260 301 364 388 430 455 485 559 602 679 860 910 970 1,118 1,204 1,261 1,358 1,505 1,820 1,940 2,236 2,522 2,716 2,795 3,010 3,395 3,913 4,171 5,044 5,590 6,020 6,305 6,790 7,826 8,342 8,827 11,180 12,610 13,580 15,652 16,684 17,654 19,565 20,855 25,220 29,197 35,308 39,130 41,710 44,135 54,223 58,394 78,260 83,420 88,270 108,446 116,788 145,985 176,540 216,892 271,115 291,970 379,561 542,230 583,940 759,122 1,084,460 1,518,244 1,897,805 3,795,610 and 7,591,220, with no remainder.
Since 7,591,220 cannot be divided by just 1 and 7,591,220, it is not a prime number.