A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 955944 can be evenly divided by 1 2 3 4 6 8 9 11 12 17 18 22 24 33 34 36 44 51 66 68 71 72 88 99 102 132 136 142 153 187 198 204 213 264 284 306 374 396 408 426 561 568 612 639 748 781 792 852 1,122 1,207 1,224 1,278 1,496 1,562 1,683 1,704 2,244 2,343 2,414 2,556 3,124 3,366 3,621 4,488 4,686 4,828 5,112 6,248 6,732 7,029 7,242 9,372 9,656 10,863 13,277 13,464 14,058 14,484 18,744 21,726 26,554 28,116 28,968 39,831 43,452 53,108 56,232 79,662 86,904 106,216 119,493 159,324 238,986 318,648 477,972 and 955,944, with no remainder.
Since 955,944 cannot be divided by just 1 and 955,944, it is not a prime number.