A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 212160 can be evenly divided by 1 2 3 4 5 6 8 10 12 13 15 16 17 20 24 26 30 32 34 39 40 48 51 52 60 64 65 68 78 80 85 96 102 104 120 130 136 156 160 170 192 195 204 208 221 240 255 260 272 312 320 340 390 408 416 442 480 510 520 544 624 663 680 780 816 832 884 960 1,020 1,040 1,088 1,105 1,248 1,326 1,360 1,560 1,632 1,768 2,040 2,080 2,210 2,496 2,652 2,720 3,120 3,264 3,315 3,536 4,080 4,160 4,420 5,304 5,440 6,240 6,630 7,072 8,160 8,840 10,608 12,480 13,260 14,144 16,320 17,680 21,216 26,520 35,360 42,432 53,040 70,720 106,080 and 212,160, with no remainder.
Since 212,160 cannot be divided by just 1 and 212,160, it is not a prime number.