GCF (HCF) of 21 and 25

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Greatest Common Factor of
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What is the Greatest Common Divisor of 21 and 25?

Answer

GCF (HCF) of 21 and 25 is
1

Common factors: 1

Only 1 divides both: 21 and 25 share no prime factor.

Such numbers are called coprime (relatively prime); their LCM is just the product: 21 × 25 = 525.

21 = 3 × 7

25 = 52

Prime2125Lowest power
33——
5—52—
77——

— = power 0: the prime is not a factor of this number, so it cannot be in the GCF.

GCF = 1

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GCF Table

Number 1Number 2GCF
21153
21221
21243
21251
21261
21273
21287
21303
21321
21333
21357
21363
21371
21381
21393
21401
214221
21441
21453
21461
21483
21497
21501
21513
21543
21567
21603
21693
21801
218421

FAQ

What is the Greatest Common Divisor of 21 and 25?

GCF (HCF) of 21 and 25 is 1

How to find the GCF of 21 and 25?

You can find the GCF of 21 and 25 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 21 and 25 is 1.

What prime factors do 21 and 25 share?

21 and 25 have no prime factor in common, so the only integer that divides both of them is 1 and their GCF is 1.

How does the GCF reduce the fraction 21/25?

Divide the numerator and the denominator by the GCF 1: 21 ÷ 1 = 21 and 25 ÷ 1 = 25. So 21/25 in lowest terms is 21/25.

Are 21 and 25 coprime?

Yes, 21 and 25 are coprime (relatively prime) because their Greatest Common Factor is 1.

See Also