WorkedMathGlossary

Factors of 4

The factors of 4 are 1, 2, 4. No, 4 is a composite number. Its prime factorization is 2^2.

Factors of 4
1, 2, 4
3 factors
Prime or Composite
Composite
Perfect Square
Yes
Prime Factorization
2^2
Sum of Factors
7 (3 without 4 itself)

Factor pairs of 4

Every factor has a partner that multiplies with it to give 4. Listing pairs from the outside in is the fastest way to find all the factors: once the two numbers in a pair meet in the middle (here at 2 × 2), you have them all.

PairCheck
1 and 41 × 4 = 4
2 and 22 × 2 = 4

Prime factorization of 4, step by step

Divide by the smallest prime that goes in evenly, then repeat on the result until you reach 1. The divisors you used are the prime factors.

StepDivideResult
14 ÷ 22
22 ÷ 21

So 4 = 2 × 2, written compactly as 2^2.

Divisibility checks for 4

The quick rules a student uses before dividing, applied to 4:

Divisible byRuleFor 4Result
2last digit is evenlast digit 4yes
3digit sum divisible by 3digits add to 4no
4last two digits divisible by 44 ÷ 4yes
5last digit is 0 or 5last digit 4no
6divisible by both 2 and 3even, digit sum 4no
8last three digits divisible by 84 ÷ 8no
9digit sum divisible by 9digits add to 4no
10last digit is 0last digit 4no

Frequently Asked Questions

What are the factors of 4?

The factors of 4 are 1, 2, 4.

Is 4 a prime number?

No, 4 is a composite number. Its prime factorization is 2^2.

How many factors does 4 have?

4 has 3 factors. You can get that count from the prime factorization without listing them: add 1 to each exponent in 2^2 and multiply -- (2+1) = 3.

Is 4 even or odd, and is it a perfect square?

4 is even (2 is one of its factors), and it is a perfect square: 2 × 2 = 4, which is why its factor list has an odd number of entries.

What is the sum of the factors of 4?

1 + 2 + 4 = 7. Leaving out 4 itself, the proper factors add to 3, less than 4, so 4 is a deficient number.

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