2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73
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21 has two prime factors.
No, 21 and 23 are not twin prime numbers. Twin primes are pairs of prime numbers that differ by 2, such as 3 and 5, or 11 and 13.
The prime numbers between 10 and 21 are 11, 13, 17, and 19.
factors of 21: 3, 7 prime factors of 21: 3, 7
There are 21 two-digit prime numbers.