981

981 is a natural number that comes after 980 and before 982. In number theory, it factors as 3^2 × 109, where 109 is prime. Its divisors are 1, 3, 9, 109, 327, and 981, giving it six divisors in total. The sum of its proper divisors is 449, so 981 is a deficient number (it is not perfect or abundant).

In other bases, 981 is represented as 1111010101 in binary, 1725 in octal, and 3D5 in hexadecimal. In Roman numerals, it is written as CMLXXXI.

As a year, 981 CE is a year in the 10th century. It appears in historical and astronomical chronology as a point of reference in the early medieval period.