odd, prime, palindrome · 7th positive integer

The number 7

7 is an odd prime number. It's known as often considered the luckiest number, the days of the week, the colors of the rainbow. It is the 7th positive integer.

Quick reference

Prime factorization	7 (prime)
Divisors	1, 7
Binary	111
Hexadecimal	0x7
Roman numeral	VII
Digit sum	7
Properties	odd, prime, palindrome

Why 7 is notable

Often considered the luckiest number, the days of the week, the colors of the rainbow.

Reading 7 in NumGrid context

For 7, the underlying data on this page comes from classical number theory plus NumGrid solver-derived puzzle statistics. The breakdown above is the federal record; the paragraphs below add the per-entity context that makes the headline numbers usable for a real decision rather than just a data lookup.

The methodology behind every numeric value on this page is publicly documented on the classical number theory plus NumGrid solver-derived puzzle statistics portal and described in detail on this site’s methodology page. Refresh cadence varies by underlying series; the page surfaces the as-of date for each number so readers can trace any figure back to the source release.

Practical use of this page is in combination with the comparison and ranking pages elsewhere on the site, which surface the same data for 7’s peers within positive integers within the NumGrid target pool. A single-entity reading without peer context can be misleading when an entity is an outlier on one axis but typical on another.