728
728 is the natural number that follows 727 and precedes 729. It is an even composite number with prime factorization 2^3 × 7 × 13. It can be expressed as 8 × 91 and equals 27^2 − 1, since 27^2 = 729, making 728 one less than a square. The sum of its divisors is 1680, which means the sum of its proper divisors is 952. In Roman numerals, 728 is written as DCCXXVIII. In various base representations, it is 1011011000 in binary, 1330 in octal, and 2D8 in hexadecimal.
As a year, 728 CE would have been a leap year in the Julian calendar, since years