A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 986370 can be evenly divided by 1 2 3 5 6 7 10 11 14 15 21 22 30 33 35 42 49 55 61 66 70 77 98 105 110 122 147 154 165 183 210 231 245 294 305 330 366 385 427 462 490 539 610 671 735 770 854 915 1,078 1,155 1,281 1,342 1,470 1,617 1,830 2,013 2,135 2,310 2,562 2,695 2,989 3,234 3,355 4,026 4,270 4,697 5,390 5,978 6,405 6,710 8,085 8,967 9,394 10,065 12,810 14,091 14,945 16,170 17,934 20,130 23,485 28,182 29,890 32,879 44,835 46,970 65,758 70,455 89,670 98,637 140,910 164,395 197,274 328,790 493,185 and 986,370, with no remainder.
Since 986,370 cannot be divided by just 1 and 986,370, it is not a prime number.