The Clinton campaign didn't release the number of donors which got them to their $21 million, but Obama's campaign made a big deal about the fact that its $31 million came from some 154,000 donors - a little over $200 each.
The maximum any one person can donate to a candidate for the primary campaign is $2,300. Let's say the Rich Galen for President Committee reports total donations of $2,300. And the campaign reports that came from one person.
The RG for Pres campaign better shake the trees for some new donors because that one donor is what we call "maxed out." He can not give any more.
But if 11 people each wrote a check for $200 (and one more wrote a check for $100) to get to that $2,300, then the Rich Galen Campaign can go back to them 10 more times. Each.
See why the number of donors is so important?
The Clinton campaign will remind everyone in their Rolodex that (a) she still leads in all the national polls, and (b) it's the number of votes in the caucuses and primaries which will determine the nominee, not the amount of money in the bank.
If political fundraising were poker that would be the equivalent of the previous hand's losers saying, "Shut up and deal."
Presidential campaigns stay alive as long as there is money in the bank. Barak Obama has enough money to stay in this thing for a long, long time - maybe all the way to Denver next August.