Is 123 a prime number?
No, 123 is not a prime number. It is divisible by 3: 123 = 3 × 41.
Is 123 prime?
Pick any whole number from 1 to 10,000.
How to work it out
- 1
A prime number has exactly two factors: 1 and itself.
- 2
It is enough to test the primes up to √123 ≈ 11.09. If none of them divides 123, it is prime.
- 3
3 divides 123 exactly, so it is not prime. Its prime factorisation is
LaTeX source of the formulas on this page
\[ 123 = 3 \times 41 \]
Testing 123 by the primes up to its square root
| Prime | Division | Result |
|---|---|---|
| 2 | 123 ÷ 2 | leaves 1 |
| 3 | 123 ÷ 3 | divides exactly (41) |
| 5 | 123 ÷ 5 | leaves 3 |
| 7 | 123 ÷ 7 | leaves 4 |
| 11 | 123 ÷ 11 | leaves 2 |
Questions
Is 123 a prime number?
No, 123 is not a prime number. It is divisible by 3: 123 = 3 × 41.
What is the next prime after 123?
127.
What is the prime number before 123?
113.
What are the factors of 123?
1, 3, 41, 123.