A factor.
A number that divides evenly into another number is called a factor.
factor
When it divides evenly into another number.
. . . factor or divisor.
A number that divides into another number evenly is said to be a factor of that number.
A factor divides evenly into a given number.
A factor divides evenly into a given number.
Factors, such as 12 or 24
A number that divides into a whole number evenly is called a "factor" of that number.
You just divide it by 21 and if there is no remainder then it went in evenly.
The mathematical concept of division is related to the divides notation by indicating how many times one number can be evenly divided by another number. The divides notation, represented by the symbol "", is used to show that a number divides evenly into another number without leaving a remainder. In other words, if one number divides another number without any remainder, it is represented using the divides notation.
A factor or divisor.