A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 5557500 can be evenly divided by 1 2 3 4 5 6 9 10 12 13 15 18 19 20 25 26 30 36 38 39 45 50 52 57 60 65 75 76 78 90 95 100 114 117 125 130 150 156 171 180 190 195 225 228 234 247 250 260 285 300 325 342 375 380 390 450 468 475 494 500 570 585 625 650 684 741 750 780 855 900 950 975 988 1,125 1,140 1,170 1,235 1,250 1,300 1,425 1,482 1,500 1,625 1,710 1,875 1,900 1,950 2,223 2,250 2,340 2,375 2,470 2,500 2,850 2,925 2,964 3,250 3,420 3,705 3,750 3,900 4,275 4,446 4,500 4,750 4,875 4,940 5,625 5,700 5,850 6,175 6,500 7,125 7,410 7,500 8,125 8,550 8,892 9,500 9,750 11,115 11,250 11,700 11,875 12,350 14,250 14,625 14,820 16,250 17,100 18,525 19,500 21,375 22,230 22,500 23,750 24,375 24,700 28,500 29,250 30,875 32,500 35,625 37,050 42,750 44,460 47,500 48,750 55,575 58,500 61,750 71,250 73,125 74,100 85,500 92,625 97,500 106,875 111,150 123,500 142,500 146,250 154,375 185,250 213,750 222,300 277,875 292,500 308,750 370,500 427,500 463,125 555,750 617,500 926,250 1,111,500 1,389,375 1,852,500 2,778,750 and 5,557,500, with no remainder.
Since 5,557,500 cannot be divided by just 1 and 5,557,500, it is not a prime number.