Is 123 a prime number?

Prime Number Checker
Number

Is 123 a prime or composite number?

Answer

Number 123 is not a Prime

123 = 3 × 41

123 has 4 divisors — 1, 3, 41 and 123; a prime has exactly two: 1 and itself.

Primes up to √123

11² = 121 ≤ 123 < 144 = 12², so it is enough to try primes up to 11

  • ÷2 does not divide
  • ÷3 divides

123 ÷ 3 = 41 — 3 divides 123, so 123 is composite

Nearest primes: 113 and 127

Related Calculations

See Also

Prime numbers list

NumberIs Prime
106No: 2 × 53
107Yes
108No: 2² × 3³
109Yes
110No: 2 × 5 × 11
111No: 3 × 37
112No: 2⁴ × 7
113Yes
114No: 2 × 3 × 19
115No: 5 × 23
117No: 3² × 13
119No: 7 × 17
120No: 2³ × 3 × 5
121No: 11²
122No: 2 × 61
123No: 3 × 41
125No: 5³
126No: 2 × 3² × 7
127Yes
128No: 2⁷
129No: 3 × 43
130No: 2 × 5 × 13
131Yes
132No: 2² × 3 × 11
133No: 7 × 19
134No: 2 × 67
135No: 3³ × 5
136No: 2³ × 17
137Yes
138No: 2 × 3 × 23

FAQ

Is 123 a prime or composite number?

Number 123 is not a Prime

How many factors are in a number 123?

4

How to check if 123 is prime?

Divide 123 by the primes in order: 11² = 121 ≤ 123 < 144 = 12², so it is enough to try primes up to 11. The first one that divides it is 3: 123 ÷ 3 = 41, so 123 is composite.

See Also