A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4028000 can be evenly divided by 1 2 4 5 8 10 16 19 20 25 32 38 40 50 53 76 80 95 100 106 125 152 160 190 200 212 250 265 304 380 400 424 475 500 530 608 760 800 848 950 1,000 1,007 1,060 1,325 1,520 1,696 1,900 2,000 2,014 2,120 2,375 2,650 3,040 3,800 4,000 4,028 4,240 4,750 5,035 5,300 6,625 7,600 8,056 8,480 9,500 10,070 10,600 13,250 15,200 16,112 19,000 20,140 21,200 25,175 26,500 32,224 38,000 40,280 42,400 50,350 53,000 76,000 80,560 100,700 106,000 125,875 161,120 201,400 212,000 251,750 402,800 503,500 805,600 1,007,000 2,014,000 and 4,028,000, with no remainder.
Since 4,028,000 cannot be divided by just 1 and 4,028,000, it is not a prime number.