A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 2775500 can be evenly divided by 1 2 4 5 7 10 13 14 20 25 26 28 35 50 52 61 65 70 91 100 122 125 130 140 175 182 244 250 260 305 325 350 364 427 455 500 610 650 700 793 854 875 910 1,220 1,300 1,525 1,586 1,625 1,708 1,750 1,820 2,135 2,275 3,050 3,172 3,250 3,500 3,965 4,270 4,550 5,551 6,100 6,500 7,625 7,930 8,540 9,100 10,675 11,102 11,375 15,250 15,860 19,825 21,350 22,204 22,750 27,755 30,500 39,650 42,700 45,500 53,375 55,510 79,300 99,125 106,750 111,020 138,775 198,250 213,500 277,550 396,500 555,100 693,875 1,387,750 and 2,775,500, with no remainder.
Since 2,775,500 cannot be divided by just 1 and 2,775,500, it is not a prime number.