No common factors other than 1.

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)

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

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)

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

See: Factor