9981809 has 2 divisors, whose sum is σ = 9981810. Its totient is φ = 9981808.

The previous prime is 9981799. The next prime is 9981847. The reversal of 9981809 is 9081899.

9981809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6390784 + 3591025 = 2528^2 + 1895^2 .

It is a cyclic number.

It is not a de Polignac number, because 9981809 - 2²⁰ = 8933233 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 9981809.

It is not a weakly prime, because it can be changed into another prime (9981869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4990904 + 4990905.

It is an arithmetic number, because the mean of its divisors is an integer number (4990905).

Almost surely, 2^9981809 is an apocalyptic number.

It is an amenable number.

9981809 is a deficient number, since it is larger than the sum of its proper divisors (1).

9981809 is an equidigital number, since it uses as much as digits as its factorization.

9981809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 44.

The square root of 9981809 is about 3159.4001012851. The cubic root of 9981809 is about 215.3127519705.

The spelling of 9981809 in words is "nine million, nine hundred eighty-one thousand, eight hundred nine".