A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 750720 can be evenly divided by 1 2 3 4 5 6 8 10 12 15 16 17 20 23 24 30 32 34 40 46 48 51 60 64 68 69 80 85 92 96 102 115 120 128 136 138 160 170 184 192 204 230 240 255 272 276 320 340 345 368 384 391 408 460 480 510 544 552 640 680 690 736 782 816 920 960 1,020 1,088 1,104 1,173 1,360 1,380 1,472 1,564 1,632 1,840 1,920 1,955 2,040 2,176 2,208 2,346 2,720 2,760 2,944 3,128 3,264 3,680 3,910 4,080 4,416 4,692 5,440 5,520 5,865 6,256 6,528 7,360 7,820 8,160 8,832 9,384 10,880 11,040 11,730 12,512 14,720 15,640 16,320 18,768 22,080 23,460 25,024 31,280 32,640 37,536 44,160 46,920 50,048 62,560 75,072 93,840 125,120 150,144 187,680 250,240 375,360 and 750,720, with no remainder.
Since 750,720 cannot be divided by just 1 and 750,720, it is not a prime number.