Technically, it depends how often you compund the interest---yearly, monthly, semimonthly, daily, or semi minutely.
Kinda a diminishing return thing, the more frequent the compounding the less additonal benefit you get. You gotta read the fine print to be sure.
But checking my HP calculator--------1.06 (Y to the X) four times 21000 yields $26,512.0162.------which would represent yearly compounding------$26,602.1717 would represent semi-annual-----$26,680.2723 monthly, $26,695.7061 daily compounding including the leap year day.------I could go on but no chart necesssary to know you are probably being cheated.------and some of the calculation assumtions get dubious----do I divide .06 by 365 or 365.25?------and I don't want to hear from that astronmer type pointing out the solar year is only approximated by 365.25.
But wanna bet that the bank gives you less generous compounding terms when they are borrowing vs. Lending?