One.
The least factor of any number is 1.
The least common factor of any set of numbers is 1.
None. The least common factor is defined only for two or more numbers: one number cannot have a LCF. In any case, the least factor of any number is 1. So 91 cannot be a least common factor of any number since 1 is a factor and 1 is less than 91.
Any even number has at least one even factor.
The least common factor of any number or set of numbers is 1.
Every number has 1 as its factor and 1 is the smallest factor of any number. So least common factor of two or more numbers is always 1. Therefore, least common factor of 23 and 25 is 1.
The least common factor of any set of numbers is 1.
The number one is a factor of every number.
The least common factor of any two positive number is always 1.
The least common factor of any two positive number is always 1.
The least common factor of any set of integers is 1.
The number one goes into every number making the the least (lowest) common factor.