9805 has 8 divisors (see below), whose sum is σ = 12312. Its totient is φ = 7488.

The previous prime is 9803. The next prime is 9811. The reversal of 9805 is 5089.

9805 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 3721 + 6084 = 61^2 + 78^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 9805 - 2¹ = 9803 is a prime.

It is a super-2 number, since 2×9805² = 192276050, which contains 22 as substring.

It is a Duffinian number.

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 159 + ... + 211.

It is an arithmetic number, because the mean of its divisors is an integer number (1539).

2⁹⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

9805 is a deficient number, since it is larger than the sum of its proper divisors (2507).

9805 is a wasteful number, since it uses less digits than its factorization.

9805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 9805 is about 99.0201999594. The cubic root of 9805 is about 21.4033884057.

It can be divided in two parts, 980 and 5, that multiplied together give a square (4900 = 70²).

The spelling of 9805 in words is "nine thousand, eight hundred five".