While most people will regard Tuesday's date with a smile and others will seize on it as a great marketing ploy, there are a few who are convinced earthquakes, floods or any number of disasters will befall the world.
In response, bookmakers in the United States have been giving odds on Devil's day calamities as the approach of the ominous date this time round gives rise to a flurry of cases of fear of the number 666 -- technically termed hexakosioihexekontahexaphobia.
"It is of course just a symbolic number, but many people are nervous," said the chancellor of Hong Kong's Catholic diocese Father Lawrence Lee.
The figure 666 is named the "number of the beast" in the closing chapter of the Bible, the "Book of Revelations", otherwise known as "The Apocalypse of John".
Chapter 13, Verse 18 of the book, with its apparent reference to the coming of the Devil, has long puzzled scholars and demonologists and fed the fantasies of conspiracy theorists and writers of ghost stories.
The general opinion among learned Christians, however, is that it doesn't refer to the Devil at all, but more likely the Roman Emperors Nero or Domitian, who ordered the widespread extermination of early Christians.
That, however, hasn't stopped many people regarding the number as the very mark of the antichrist, a symbol they claim to have found hidden in all sorts of things, including Tuesday's date.
"Numbers are symbols and are mysterious -- they could mean one thing or they could mean something else," said Phee-seng Kan, professor of religion and theology at the Hong Kong Baptist University.
Christian fundamentalists, especially in the US, appear most concerned about Tuesday.
The Raptureready.com website, which gives each day an index for the likelihood of the coming of the Biblical End of Days, ranks Tuesday as a very high 154.
The highest-ranked day ever was in September 2001 after the terror attacks on the US.
It's not just religious extremists that are spooked.
Police in Denver, Colorado, have said they'll step up patrols in case there's a sudden rise in devilish activity.
"It's been a conscious question among some of our folks, so they've been on the lookout for something," Lance Clem, spokesman for the Colorado Department of Public Safety was quoted as saying on the Science Daily website. "But they haven't seen anything."
Others see the coming of 6/6/6 as an opportunity to have a party.
The residents of the aptly named American town of Hell in Michigan plan a huge knees-up in what the local mayor John Colone says will give people the chance to say they "partied in Hell on 666".
Beliefs in the number's Satanic links have been amplified in recent years by box-office hit movies such as "The Omen" and "The Exorcist" and by novels, such as those by horror writer Stephen King.
The release last week of the movie adaptation of author Dan Brown's best-selling novel "The Da Vinci Code" has also raised awareness of the symbolic nature of the date.
In the book, an expert in symbols uncovers a series of coded messages associated with the murder of an art historian to piece together new revelations about the life of Christ.
The anxieties surrounding Tuesday's arrival are similar to those felt at the approach of the turn of the 21st century.
Then, many people believed the clocks in computers that guide our everyday lives would switch to zero and stop, precipitating disastrous breakdowns in communications and other essential infrastructure.
Professor Kang blamed such hysteria on ignorance of the origin of symbols.
"They can only be interpreted properly with knowledge of their tradition," Kang said.
-by Mark McCord
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