A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4240740 can be evenly divided by 1 2 3 4 5 6 7 10 12 14 15 20 21 23 28 30 35 42 46 60 69 70 84 92 105 115 138 140 161 210 230 276 322 345 420 439 460 483 644 690 805 878 966 1,317 1,380 1,610 1,756 1,932 2,195 2,415 2,634 3,073 3,220 4,390 4,830 5,268 6,146 6,585 8,780 9,219 9,660 10,097 12,292 13,170 15,365 18,438 20,194 26,340 30,291 30,730 36,876 40,388 46,095 50,485 60,582 61,460 70,679 92,190 100,970 121,164 141,358 151,455 184,380 201,940 212,037 282,716 302,910 353,395 424,074 605,820 706,790 848,148 1,060,185 1,413,580 2,120,370 and 4,240,740, with no remainder.
Since 4,240,740 cannot be divided by just 1 and 4,240,740, it is not a prime number.