even, composite · 18th positive integer
The number 18
18 is an even composite number. It is the 18th positive integer.
Quick reference
| Prime factorization | 2 × 3 × 3 |
| Divisors | 1, 2, 3, 6, 9, 18 |
| Binary | 10010 |
| Hexadecimal | 0x12 |
| Roman numeral | XVIII |
| Digit sum | 9 |
| Properties | even, composite |
Reading 18 in NumGrid context
For 18, 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.
Every number on this page links back to classical number theory plus NumGrid solver-derived puzzle statistics; the methodology page describes the inputs, refresh cadence, and known limitations of the underlying data product.
For readers using this page as a decision input, the related-entity pages elsewhere on the site provide the comparison set. The most useful comparison for 18 is typically a peer within positive integers within the NumGrid target pool with similar size, similar exposure, or similar geography — not the national-level summary alone.
Frequently asked
Is 18 a prime number?
No. 18 is composite. Its prime factorization is 2 × 3 × 3.
What are the factors of 18?
The factors (divisors) of 18 are 1, 2, 3, 6, 9, 18.
What is 18 in binary?
18 in binary is 10010. In hexadecimal it's 12.
What is 18 as a Roman numeral?
18 in Roman numerals is XVIII.
What's the digit sum of 18?
Adding the digits of 18: 1 + 8 = 9.