809900 has 72 divisors (see below), whose sum is σ = 2187360. Its totient is φ = 253440.

The previous prime is 809891. The next prime is 809903. The reversal of 809900 is 9908.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 809900.

It is not an unprimeable number, because it can be changed into a prime (809903) by changing a digit.

809900 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9056 + ... + 9144.

It is an arithmetic number, because the mean of its divisors is an integer number (30380).

2⁸⁰⁹⁹⁰⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 809900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1093680).

809900 is an abundant number, since it is smaller than the sum of its proper divisors (1377460).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

809900 is a wasteful number, since it uses less digits than its factorization.

809900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123 (or 116 counting only the distinct ones).

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

The square root of 809900 is about 899.9444427297. The cubic root of 809900 is about 93.2131389312.

The spelling of 809900 in words is "eight hundred nine thousand, nine hundred".