The New Republic’s Christopher Beam explains the popularity in China of apparently inscrutable numerical web addresses:
[…] For many Chinese, numbers are easier to remember than Latin characters. Sure, Chinese children learn the pinyin system that uses the Roman alphabet to spell out Mandarin words (for example, the word for “Internet,” 网络, is spelled wangluo in pinyin). And yes, Arabic numerals (1-2-3) are technically just as much a foreign import as the Roman alphabet (A-B-C). But most Chinese are more familiar with numbers than letters, especially those who didn’t go to college. To many, “Hotmail.com” might as well be Cyrillic.
[…] Digits are even more convenient when you consider that the words for numbers are homophones for other words. The URL for the massive e-commerce site Alibaba, for example, is 1688.com, pronounced “yow-leeyoh-ba-ba”—close enough! Those digits can just as often have individual meanings. The video sharing site 6.cn works because the word for “six” is a near-homophone for the word “to stream.” The number five is pronounced wu, which sounds like wo, which means “I.” The number one is pronounced yao, which with a different tone means “want.” So the job-hunting site 51job.com sounds a lot like “I want a job.” Likewise, to order McDonalds’ delivery online, just go to 4008-517-517.com, the “517” of which sounds a bit like “I want to eat.” […] [Source]