Yes, both numbers are significant and you can say that 13 has two significant figures.
It becomes a bit trickier with a number like 10 or 100 (i.e., when zeros are involved). For example, the number 100 has one significant figure but if you wrote 100. then you have three significant figures with the decimal point indicating that the zeros are significant.
Additionally, if you have the number 100 and you know that only two of the numbers are significant, then you would use scientific notation and write 1.0 x 10^2. That gives you 100 to two significant figures.
Hope that helps.