A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 4637178 can be evenly divided by 1 2 3 6 7 9 13 14 18 19 21 26 38 39 42 57 63 78 91 114 117 126 133 149 171 182 234 247 266 273 298 342 399 447 494 546 741 798 819 894 1,043 1,197 1,341 1,482 1,638 1,729 1,937 2,086 2,223 2,394 2,682 2,831 3,129 3,458 3,874 4,446 5,187 5,662 5,811 6,258 8,493 9,387 10,374 11,622 13,559 15,561 16,986 17,433 18,774 19,817 25,479 27,118 31,122 34,866 36,803 39,634 40,677 50,958 59,451 73,606 81,354 110,409 118,902 122,031 178,353 220,818 244,062 257,621 331,227 356,706 515,242 662,454 772,863 1,545,726 2,318,589 and 4,637,178, with no remainder.
Since 4,637,178 cannot be divided by just 1 and 4,637,178, it is not a prime number.