661 is a prime number from 601-700. 661 has 2 factors, 1 and 661. It is the 121st prime number, and the twelfth prime number from 601-700. 661 can be turned upside down to give 199, which is also a prime number.
Relationship with other odd numbers
The numbers before
- The previous prime number is 659.
- There are no odd numbers between 659 and 661. As a result, they are twin primes.
- The previous prime number before 659 is 653.
The numbers after
- The next prime number is 673.
- Notably, 667 is the product of 23 and 29, while 671 is divisible by 11. They are both composite numbers.
- 677 is the next prime number after 673.
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