If a natural number is equal to the sum of all positive factors except itself, then such a number is called a perfect number, and only five such numbers have been found so far.
The other four are 28 = 1+2+4+7+ 14.
496= 12+4+8+ 16+3 1+62+ 124+248
8 128= 1+2+4+8+32+64+ 127+254+508+ 10 16+2032+4064
There is also a 33550336.
These numbers were called auspicious numbers in ancient times.