Ignoring black cell in age calculation

[pangs]

Hi, I used this formula for calculating the age
=DATEDIF(K21,TODAY(),"Y") & " Years, " & DATEDIF(K21,TODAY(),"YM") & " Months, " & DATEDIF(K21,TODAY(),"MD") & " Days"
Is there a formula to keep the cell blank if there is no data in the date of birth column?

 

[oldbrewer]

start formula with =if(k21="","",datedif.................................... )