To find all the divisors of the number 20,789,680:
- 1. Decompose the number into prime factors.
- See how you can find out how many factors (divisors) the number has, without actually calculating them.
- 2. Multiply the prime factors in all their unique combinations, that yield different results.
1. Carry out the prime factorization of the number 20,789,680:
The prime factorization of a number: finding the prime numbers that multiply together to make that number.
20,789,680 = 24 × 5 × 151 × 1,721
20,789,680 is not a prime number but a composite one.
- Prime number: a natural number that is divisible (divided evenly) only by 1 and itself. A prime number has exactly two factors: 1 and the number itself.
- Examples of prime numbers: 2 (factors 1, 2), 3 (factors 1, 3), 5 (factors 1, 5), 7 (factors 1, 7), 11 (factors 1, 11), 13 (factors 1, 13), ...
- Composite number: a natural number that has at least one factor other than 1 and itself. So it is neither a prime number nor 1.
- Examples of composite numbers: 4 (it has 3 factors: 1, 2, 4), 6 (it has 4 factors: 1, 2, 3, 6), 8 (it has 4 factors: 1, 2, 4, 8), 9 (it has 3 factors: 1, 3, 9), 10 (it has 4 factors: 1, 2, 5, 10), 12 (it has 6 factors: 1, 2, 3, 4, 6, 12), ...
How to count the number of factors of a number?
Without actually finding the factors
- If a number N is prime factorized as:
N = am × bk × cz
where a, b, c are the prime factors and m, k, z are their exponents, natural numbers, .... - ...
- Then the number of factors of the number N can be calculated as:
n = (m + 1) × (k + 1) × (z + 1) - ...
- In our case, the number of factors is calculated as:
- n = (4 + 1) × (1 + 1) × (1 + 1) × (1 + 1) = 5 × 2 × 2 × 2 = 40
But to actually calculate the factors, see below...
2. Multiply the prime factors of the number 20,789,680
- Multiply the prime factors involved in the prime factorization of the number in all their unique combinations, that give different results.
- Also consider the exponents of these prime factors.
- Also add 1 to the list of factors (divisors). All the numbers are divisible by 1.
All the factors (divisors) are listed below - in ascending order
The list of factors (divisors):
Numbers other than 1 that are not prime factors are composite factors (divisors).
neither prime nor composite =
1
prime factor =
2
composite factor = 2
2 =
4
prime factor =
5
composite factor = 2
3 =
8
composite factor = 2 × 5 =
10
composite factor = 2
4 =
16
composite factor = 2
2 × 5 =
20
composite factor = 2
3 × 5 =
40
composite factor = 2
4 × 5 =
80
prime factor =
151
composite factor = 2 × 151 =
302
composite factor = 2
2 × 151 =
604
composite factor = 5 × 151 =
755
composite factor = 2
3 × 151 =
1,208
composite factor = 2 × 5 × 151 =
1,510
prime factor =
1,721
composite factor = 2
4 × 151 =
2,416
composite factor = 2
2 × 5 × 151 =
3,020
composite factor = 2 × 1,721 =
3,442
This list continues below...
... This list continues from above
composite factor = 2
3 × 5 × 151 =
6,040
composite factor = 2
2 × 1,721 =
6,884
composite factor = 5 × 1,721 =
8,605
composite factor = 2
4 × 5 × 151 =
12,080
composite factor = 2
3 × 1,721 =
13,768
composite factor = 2 × 5 × 1,721 =
17,210
composite factor = 2
4 × 1,721 =
27,536
composite factor = 2
2 × 5 × 1,721 =
34,420
composite factor = 2
3 × 5 × 1,721 =
68,840
composite factor = 2
4 × 5 × 1,721 =
137,680
composite factor = 151 × 1,721 =
259,871
composite factor = 2 × 151 × 1,721 =
519,742
composite factor = 2
2 × 151 × 1,721 =
1,039,484
composite factor = 5 × 151 × 1,721 =
1,299,355
composite factor = 2
3 × 151 × 1,721 =
2,078,968
composite factor = 2 × 5 × 151 × 1,721 =
2,598,710
composite factor = 2
4 × 151 × 1,721 =
4,157,936
composite factor = 2
2 × 5 × 151 × 1,721 =
5,197,420
composite factor = 2
3 × 5 × 151 × 1,721 =
10,394,840
composite factor = 2
4 × 5 × 151 × 1,721 =
20,789,680
40 factors (divisors)
What times what is 20,789,680?
What number multiplied by what number equals 20,789,680?
All the combinations of any two natural numbers whose product equals 20,789,680.
1 × 20,789,680 = 20,789,680
2 × 10,394,840 = 20,789,680
4 × 5,197,420 = 20,789,680
5 × 4,157,936 = 20,789,680
8 × 2,598,710 = 20,789,680
10 × 2,078,968 = 20,789,680
16 × 1,299,355 = 20,789,680
20 × 1,039,484 = 20,789,680
40 × 519,742 = 20,789,680
80 × 259,871 = 20,789,680
151 × 137,680 = 20,789,680
302 × 68,840 = 20,789,680
604 × 34,420 = 20,789,680
755 × 27,536 = 20,789,680
1,208 × 17,210 = 20,789,680
1,510 × 13,768 = 20,789,680
1,721 × 12,080 = 20,789,680
2,416 × 8,605 = 20,789,680
3,020 × 6,884 = 20,789,680
3,442 × 6,040 = 20,789,680
20 unique multiplications The final answer:
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