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GCF (HCF) of 16 and 21

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What is the Greatest Common Divisor of 16 and 21?

Answer

GCF (HCF) of 16 and 21 is

1

Common factors: 1

Only 1 divides both: 16 and 21 share no prime factor.

Such numbers are called coprime (relatively prime); their LCM is just the product: 16 × 21 = 336.

16 = 2⁴

21 = 3 × 7

Prime	16	21	Lowest power
2	2⁴	—	—
3	—	3	—
7	—	7	—

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

GCF = 1

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See Also

Least Common Multiple - Find the Least Common Multiple (LCM) of two numbers
Greatest Common Factor of 3 Numbers - Find the Greatest Common Factor (GCF) of three numbers
Least Common Multiple of 3 Numbers - Find the Least Common Multiple (LCM) of three numbers

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What is the GCF (HCF) of 16 and 21. The GCF of 16 and 21 is 1 — the biggest number that can divide both integers. Step-by-step GCF (GCD) calculation by factoring.

https://calculat.io/en/number/greatest-common-factor-of/16--21/generated.jpg

GCF Table

Number 1	Number 2	GCF
16	12	4
16	18	2
16	19	1
16	20	4
16	21	1
16	22	2
16	23	1
16	24	8
16	25	1
16	26	2
16	27	1
16	28	4
16	30	2
16	32	16
16	33	1
16	34	2
16	35	1
16	36	4
16	38	2
16	39	1
16	40	8
16	42	2
16	43	1
16	44	4
16	45	1
16	46	2
16	48	16
16	49	1
16	50	2
16	53	1

FAQ

What is the Greatest Common Divisor of 16 and 21?

GCF (HCF) of 16 and 21 is 1

How to find the GCF of 16 and 21?

You can find the GCF of 16 and 21 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 16 and 21 is 1.

What prime factors do 16 and 21 share?

16 and 21 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 16/21?

Divide the numerator and the denominator by the GCF 1: 16 ÷ 1 = 16 and 21 ÷ 1 = 21. So 16/21 in lowest terms is 16/21.

Are 16 and 21 coprime?

Yes, 16 and 21 are coprime (relatively prime) because their Greatest Common Factor is 1.