A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 616140 can be evenly divided by 1 2 3 4 5 6 7 9 10 12 14 15 18 20 21 27 28 30 35 36 42 45 54 60 63 70 84 90 105 108 126 135 140 163 180 189 210 252 270 315 326 378 420 489 540 630 652 756 815 945 978 1,141 1,260 1,467 1,630 1,890 1,956 2,282 2,445 2,934 3,260 3,423 3,780 4,401 4,564 4,890 5,705 5,868 6,846 7,335 8,802 9,780 10,269 11,410 13,692 14,670 17,115 17,604 20,538 22,005 22,820 29,340 30,807 34,230 41,076 44,010 51,345 61,614 68,460 88,020 102,690 123,228 154,035 205,380 308,070 and 616,140, with no remainder.
Since 616,140 cannot be divided by just 1 and 616,140, it is not a prime number.