Sign up ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

I vaguely remember there is a notion of numbers rich in divisors, i.e. (number of divisors of N)/N is comparatively large. What's their name? Given a number M, how could I find such a number in its neighbourhood?

share|cite|improve this question
Primorials $p_n \#$ have quite some divisors. –  draks ... Sep 24 '12 at 10:52

2 Answers 2

This might be interesting:

Moreover if you care about sums:

share|cite|improve this answer
wow I never knew pure mathematicians even studied these things. The names themselves are funny enough. –  Xiaowen Li Sep 24 '12 at 11:48

You might be thinking about smooth numbers.

How to find such things? I suppose you could just multiply small numbers together until you are within the "neighbourhood". If you overshoot, take out some factors and replace them with other factors.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.