What Is a Prime Number?

A prime number is a whole number greater than 1 that has exactly two factors:

  • 1
  • itself

If a number has more than two factors, it is not a prime number—it is called a composite number.

Step-by-Step Check: Is 57 Prime?

Let’s determine whether 57 is a prime number.

Step 1: Try dividing by 2

$$ 57 \div 2 = 28.5 \quad \text{❌ Not divisible} $$

Step 2: Try dividing by 3

[ 57 \div 3 = 19 \quad \text{✅ Divisible} ]

Since 57 has factors other than 1 and itself, it is not a prime number.

Conclusion

  • Prime numbers have exactly two distinct factors: (1) and itself.
  • (57 = 3 \times 19), so it has more than two factors.

[ \boxed{57\ \text{is not a prime number.}} ]