Back when I first started really understanding how computers worked (on my second computer, a 386) I used to compare the size of hard drives and cds to the number of floppies it would take to hold all that data. For instance and 100MB hard drive is equivalent to ~69 3.5 HD floppy disks.

So I was wondering how many floppies you would need to store every possible MD5 hash, I whipped up a little python program to help me. I also added some other units to give you some idea of the magnitude of the numbers involved. Note that I am using the programmers version of megabyte (1024*1024 bytes) etc.

Space needed to store all possible MD5 hashes
5444517870735015415413993718908291383296	bytes
5316911983139663491615228241121378304	kilobytes
5192296858534827628530496329220096	megabytes
3692299988291432980288352945223179	3.5 high density floppies
7988149013130504043893071275723	cds 650Mb version
5070602400912917605986812821504	gigabytes
1078851574833345673835790826676	dvds single sided single layer
202824096036516704239472512860	blueray single layer disks
101412048018258352119736256430	blueray double layer disks
13611294676837538538534984297	units of the largest hardrive in my house
4951760157141521099596496896	terabytes
3961408125713216879677197516	human brains
264093875047547791978479834	libraries of congress
4835703278458516698824704	petabytes
859680582837069635346614	google server farms (estimated)
54445178707350154154139	Data's (From Star Trek)
4722366482869645213696	exabytes
29514790517935282585	units of world storage as of 2006
4722366482869645213	units of world storage projected for 2010
4611686018427387904	zettabytes
2419785720326673517	units of information in 1 gram of DNA
4503599627370496	yottabytes

If you want the English name of the number, then use this page

And for comparison here is this table:

Space needed to store all 32 bit integers
17179869184	bytes
16777216	kilobytes
16384	megabytes
11650	3.5 high density floppies
25	cds 650Mb version
16	gigabytes
3	dvds single sided single layer