A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 6858324 can be evenly divided by 1 2 3 4 6 9 11 12 18 22 23 27 33 36 44 46 54 66 69 92 99 108 132 138 198 207 251 253 276 297 396 414 502 506 594 621 753 759 828 1,004 1,012 1,188 1,242 1,506 1,518 2,259 2,277 2,484 2,761 3,012 3,036 4,518 4,554 5,522 5,773 6,777 6,831 8,283 9,036 9,108 11,044 11,546 13,554 13,662 16,566 17,319 23,092 24,849 27,108 27,324 33,132 34,638 49,698 51,957 63,503 69,276 74,547 99,396 103,914 127,006 149,094 155,871 190,509 207,828 254,012 298,188 311,742 381,018 571,527 623,484 762,036 1,143,054 1,714,581 2,286,108 3,429,162 and 6,858,324, with no remainder.
Since 6,858,324 cannot be divided by just 1 and 6,858,324, it is not a prime number.