Prime Factorization of 21

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Prime Factors of

What is the Prime Factorization of 21?

Answer

Prime Factors of 21:
3, 7

21 = 3 × 7 · composite · 4 factors

Division ladder

213
77
1

Left: what is left; right: the smallest prime that divides it; 1 at the bottom.

Second way — factor tree
2137

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Prime Factorization Table

NumberPrime Factors
62, 3
77
823
932
102, 5
1111
1222 × 3
1313
142, 7
153, 5
1624
1717
182 × 32
1919
2022 × 5
213, 7
222, 11
2323
2423 × 3
2552
262, 13
2733
2822 × 7
2929
302, 3, 5
3131
3225
333, 11
342, 17
355, 7

FAQ

What is the Prime Factorization of 21?

Prime Factors of 21: 3, 7

How many prime factors does 21 have?

Number 21 has 2 prime factors, all different.

How can you check the prime factorization of 21?

Multiply the factors back together: 3 × 7 = 21. Every factor is prime, so nothing splits any further and this decomposition is the only one that exists.

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