In addition we can say of the number 138 that it is even
138 is an even number, as it is divisible by 2 : 138/2 = 69
The factors for 138 are all the numbers between -138 and 138 , which divide 138 without leaving any remainder. Since 138 divided by -138 is an integer, -138 is a factor of 138 .
Since 138 divided by -138 is a whole number, -138 is a factor of 138
Since 138 divided by -69 is a whole number, -69 is a factor of 138
Since 138 divided by -46 is a whole number, -46 is a factor of 138
Since 138 divided by -23 is a whole number, -23 is a factor of 138
Since 138 divided by -6 is a whole number, -6 is a factor of 138
Since 138 divided by -3 is a whole number, -3 is a factor of 138
Since 138 divided by -2 is a whole number, -2 is a factor of 138
Since 138 divided by -1 is a whole number, -1 is a factor of 138
Multiples of 138 are all integers divisible by 138 , i.e. the remainder of the full division by 138 is zero. There are infinite multiples of 138. The smallest multiples of 138 are:
It is possible to determine using mathematical techniques whether an integer is prime or not.
for 138, the answer is: No, 138 is not a prime number.
To know the primality of an integer, we can use several algorithms. The most naive is to try all divisors below the number you want to know if it is prime (in our case 138). We can already eliminate even numbers bigger than 2 (then 4 , 6 , 8 ...). Besides, we can stop at the square root of the number in question (here 11.747 ). Historically, the Eratosthenes screen (which dates back to Antiquity) uses this technique relatively effectively.
More modern techniques include the Atkin screen, probabilistic tests, or the cyclotomic test.
Previous prime number: 137
Next prime number: 139