In the novel fires are at first thought to be accidents or arson. It turns out that any computer (the payroll program, the computer operated camera shooting spaceship models in an effects house) that stumbles across this number (20-30 digits but with no zeroes) will ... I don't remember exactly ... summon a fire spirit?

One of the clues was an ancient manuscript that when scanned started a fire. The concept of 'zero' coming after it was written.

I want to say the date of the novel was the 1980s.