My dad told me that a number is another name for a joint.
they probably mixed the love theme with the drug theme to create poetic tension and juxtaposition.
I've been checking out a lot of Dan songs on this website and that seems to be the general theme that I've gotten from a lot of them.

The story I read

http://en.wikipedia.org/wiki/Rikki_Don%27t_Lose_That_Number

was that "Rikki" was Rikki Ducornet, the wife of an instructor at Bard, where Don Fagen had both gone to school.

From the Wikipedia article,

"In the March 24, 2006 (2006-03-24) issue of Entertainment Weekly, in an article titled "Back to Annandale", it was revealed that Rikki Ducornet was the apparent inspiration for the song due to a friendship songwriter Donald Fagen had with Ducornet while he attended Bard College. Ducornet was pregnant and married at the time, but recalls Fagen did give her his phone number at a college party while attending Bard and said that she believed she was the subject of the song. Fagen would not confirm the story.[2]"

citation 2 for this article is the Entertainment Weekly article, available on their Web site:

http://www.ew.com/ew/article/0,,1174152,00.html

if anyone's interested.

I would assume that Entertainment Weekly's lawyers wouldn't let them print this if it were substantially untrue.

The Wikipedia article didn't really quote the article in Entertainment Weekly, but paraphrased it.

For those of you interested in the actual quote from the actual article:

http://www.ew.com/ew/article/0,,1174152_3,00.html

"Tucked in the woods behind Stone Row, down a narrow path many students never notice, sits a one-room, octagonal stone structure known as the Observatory. It is there that Fagen most wants to visit. ''I used to practice here,'' he explains, gazing around the room, which, it turns out, was converted into an office in the early '70s. This isolated space was one of Fagen's most cherished escapes. ''There was nothing in there but a grand piano,'' he says. ''I had wonderful hours in here practicing scales, things that no one else should hear, you know? I'd write tunes in here, too. And if you were rejected by someone you were in love with, you could scream. I was always in love with someone [who] ignored me completely. That was my Bard experience. There was a Sorrows of Young Werther vibe about it.''

One such unrequited crush might have been a professor's young wife named Rikki Ducornet, whose first name will be familiar to Steely Dan fans. Fagen won't admit it — he's always been extremely reluctant to explain his songs — but it's easy to imagine that Ducornet was the inspiration for one of his band's most famous tunes, ''Rikki Don't Lose That Number.'' ''I remember we had a great conversation and he did suggest I call him, which never happened,'' says Ducornet, now a well-regarded novelist and artist. ''But I know he thought I was cute. And I was cute,'' she laughs. ''I was very tempted to call him, but I thought it might be a bit risky. I was very enchanted with him and with the music. It was so evident from the get-go that he was wildly talented. Being a young faculty wife and, I believe, pregnant at the time, I behaved myself, let's say. Years later, I walked into a record store and heard his voice and thought, 'That's Fagen. And that's my name!'''

Fagen would have better luck with a former Bard student named Libby Titus, whom he encountered on campus in 1966 and married 27 years later. And that's hardly his only happy memory of the school. ''I was coming straight from a housing development in New Jersey, so it was great,'' he says. ''I loved the teachers and the girls, you know. I had friends here. Probably the only time in my life,'' he says with a laugh, ''that I actually had friends.'' "

I agree with Austinbarry~
I've always heard this described as the poor man's copyright.
Don't lose that number, send it off in a letter to yourself.
Keep the sealed/post marked envelope--with the lyrics inside
as a means to document/confirm ownership of a song.

i always thought this song was about a friend talking to a drug addict trying to get clean. leaving drug friends behind, moving away from the stuff, etc. or even an alcoholic. all of the above statements make sense also.