It is "4", because the number "4" is homophonic with the Chinese word "death", so it is regarded as the most unlucky number.
The 14-digit products are still in use:
14 stealth aircraft will fly, and if it is unlucky, it will not be named 歼 14;
such as the familiar 114 enquiry telephone. How good it is to serve everyone;
and the old brand 414 towels.
explanation of 4:
"One" was the first in Yuan Dynasty, and everyone yearned for climbing the peak. It is reasonable to establish what is the first-class level and strive for the first place. And because this "one" is pure, expert, full and complete, it is commendable to "wholeheartedly" and "follow the law";
"four" is the word of understanding. People's entrepreneurship, no matter what kind of business, always hopes to extend in all directions and flourish everywhere. A good man aims at all directions, takes the four seas as his home, and makes steady progress with benevolence, which can also be called a safe and steady life.