643 is a prime number from 601-700. 643 has 2 factors, 1 and 643. It is the 117th prime number, and the eighth prime number from 601-700.
Relationship with other odd numbers
The numbers before
- The previous prime number is 641.
- There are no odd numbers between 641 and 643. As a result, they are twin primes.
- The previous prime number before 641 is 631.
- 637 is divisible by 7, therefore not a prime number.
The numbers after
- The next prime number is 647.
- 643 and 647 are four numbers apart; therefore, they are cousin primes.
- 653 is the next prime number after 647.
- 649 is divisible by 11, therefore not a prime number.
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