Coprime

Coprime numbers have no common factors other than 1

And no fractions! Just integers, and positive factors.

21 and 22 are coprime:
• The factors of 21 are 1, 3, 7 and 21
• The factors of 22 are 1, 2, 11 and 22
(the only common factor is 1)

But 21 and 24 are NOT coprime:
• The factors of 21 are 1, 3, 7 and 21
• The factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24
(the common factors are 1 AND 3)


Put another way: there is no whole number that would divide both coprime numbers exactly (without any remainder).

Also called "relatively prime" or "mutually prime".