As others have mentioned, Math::BigInt would do the trick, if you're doing everything in Perl. However, you've also used the words "SQL" and "Sybase" in your note, which makes me think otherwise....

Before anyone can render any kind of answer, you need to provide more information:

• What is the type of the column you're trying to write into? If it's a Sybase database, are you using float, decimal (a.k.a. numeric) or (shudder) money?
• How are you talking to the database? Are you using DBI or Sybase::CTlib? They're both by the same author, Michael Peppler, but there are differences.
• When you say "Sybase isn't happy", what do you mean? Are you getting a loss-of-precision error, or do you think you're losing precision because when you query later, the value in the column doesn't look like what you think you wrote?

As you can see, there's a lot of variability possible. I'd be glad to help -- I work with Perl and Sybase on a daily basis -- but I really don't have enough to go on....