A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 384300 can be evenly divided by 1 2 3 4 5 6 7 9 10 12 14 15 18 20 21 25 28 30 35 36 42 45 50 60 61 63 70 75 84 90 100 105 122 126 140 150 175 180 183 210 225 244 252 300 305 315 350 366 420 427 450 525 549 610 630 700 732 854 900 915 1,050 1,098 1,220 1,260 1,281 1,525 1,575 1,708 1,830 2,100 2,135 2,196 2,562 2,745 3,050 3,150 3,660 3,843 4,270 4,575 5,124 5,490 6,100 6,300 6,405 7,686 8,540 9,150 10,675 10,980 12,810 13,725 15,372 18,300 19,215 21,350 25,620 27,450 32,025 38,430 42,700 54,900 64,050 76,860 96,075 128,100 192,150 and 384,300, with no remainder.
Since 384,300 cannot be divided by just 1 and 384,300, it is not a prime number.