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# Prime numbers

Prime numbers are those with only two divisors, itself and 1. There are infinities and the smallest is 2.

For example, each number that appears in the following list is prime:

### How many prime numbers are there?

The quantity is infinite and it was Euclid of Alexandria who proved it. Until today, nobody has found a formula to calculate all prime numbers.

### What is the largest prime number known?

The largest known to humanity has more than 22 million digits.

The following explains how they have been calculated and their relationship to the perfect numbers:

## Exercices

1. Prime numbers between 1 and 50:

## Ejercicios de Números Primos

2. Select the prime numbers:

## Ejercicios de Números Primos

### Factors of 36

The number 36 has 9 factors and is a composite number. To calculate the factors of 36 we divide,...

### Factors of 35

The number 35 has 4 factors and is a composite number. To calculate the factors of 35 we divide,...

### Factors of 34

The number 4 has 4 factors and is a composite number. To calculate the factors of 34 we divide,...

### Factors of 33

The number 33 has 4 factors and is a composiite number. To calculate the factors of 33 we divide,...

### Factors of 32

The number 32 has 6 factors and is a composite number. To calculate the factors of 32 we divide,...

### Factors of 31

The number 31 has 2 factors and is a prime number. To calculate the factors of 31 we divide,...

### Factors of 30

The number 30 has 8 factors and is a composite number. To calculate the factors of 30 we divide,...

### Factors of 29

The number 29 has 2 factors and is a prime number. To calculate the factors of 29 we divide,...

### Factors of 28

The number 28 has 5 factors and is a composite number. To calculate the factors of 28 we divide,...

### Factors of 27

The number 27 has 4 factors and is a composite number. To calculate the factors of 27 we divide,...