Question 100612
A rational number is defined as:
A number capable of being expressed as an integer or a quotient of integers, excluding zero as a denominator


So yes 25 is a rational number because it is an integer.
50/2 = 25 
or simply
25/1 = 25

A detailed explanation of rational numbers can be found here:

<a href="http://www.eduplace.com/math/mathsteps/7/a/index.html">Rational Numbers</a>