This is one scary number. Bloomberg has a story on how demand is drying up so fast, literally 21,000 jobs disappeared in a day. Not one week, not a few days, 1 day.

At least 21,000 jobs were targeted for elimination yesterday as employers from Hertz Global Holdings Inc. to Advanced Micro Devices Inc. grappled with recession-choked demand.

More than 20 companies said they were cutting jobs, ranging from Amonil SA, Romania’s second-biggest fertilizer maker, to Fiat SpA’s Magneti Marelli auto-parts division. Hertz, the second-largest U.S. rental-car company, said it will cut more than 4,000 jobs, as businesses and consumers slow travel because of the global recession.

“What you take away here is just how miserably profitability performed in the final quarter of ‘08,” said John Lonski, chief economist at Moody’s Capital Markets Group in New York, in an interview. “Companies cut back on staff when sales are significantly under expectation.”

If that kept up for just one month, assume 30 days in 1 month, then it would be 630,000 jobs. This tells you what a spike in layoffs this number is.