9809 has 4 divisors (see below), whose sum is σ = 10404. Its totient is φ = 9216.

The previous prime is 9803. The next prime is 9811. The reversal of 9809 is 9089.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9089 = 61 ⋅149.

It can be written as a sum of positive squares in 2 ways, for example, as 9025 + 784 = 95^2 + 28^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9809 is a prime.

It is an Ulam 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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 272 + ... + 305.

It is an arithmetic number, because the mean of its divisors is an integer number (2601).

2⁹⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

9809 is a deficient number, since it is larger than the sum of its proper divisors (595).

9809 is a wasteful number, since it uses less digits than its factorization.

9809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 594.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 9809 is about 99.0403957989. The cubic root of 9809 is about 21.4062985507.

It can be divided in two parts, 980 and 9, that added together give a palindrome (989).

The spelling of 9809 in words is "nine thousand, eight hundred nine".