Factors / Factors of 391

Factors of 391

1, 17, 23, 391

391 breaks into 2 pairs, tested up to √391 ≈ 19.8; each pair multiplies back to 391 exactly. 391's full pair list is (1, 391), (17, 23), for 4 divisors in total. 391's divisors other than 391 itself sum to just 41, 350 below 391: the common deficient case. 391 is odd, digit sum 13 for 391; none of 2-12 divide 391 evenly. 391 has 4 divisors; 390 has 16 and 392 has 12, so 390 wins here. 391 divided by its largest divisor, 23, gives 17.