A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 379440 can be evenly divided by 1 2 3 4 5 6 8 9 10 12 15 16 17 18 20 24 30 31 34 36 40 45 48 51 60 62 68 72 80 85 90 93 102 120 124 136 144 153 155 170 180 186 204 240 248 255 272 279 306 310 340 360 372 408 465 496 510 527 558 612 620 680 720 744 765 816 930 1,020 1,054 1,116 1,224 1,240 1,360 1,395 1,488 1,530 1,581 1,860 2,040 2,108 2,232 2,448 2,480 2,635 2,790 3,060 3,162 3,720 4,080 4,216 4,464 4,743 5,270 5,580 6,120 6,324 7,440 7,905 8,432 9,486 10,540 11,160 12,240 12,648 15,810 18,972 21,080 22,320 23,715 25,296 31,620 37,944 42,160 47,430 63,240 75,888 94,860 126,480 189,720 and 379,440, with no remainder.
Since 379,440 cannot be divided by just 1 and 379,440, it is not a prime number.