809640 has 96 divisors (see below), whose sum is σ = 2850120. Its totient is φ = 198144.

The previous prime is 809629. The next prime is 809701. The reversal of 809640 is 46908.

It can be written as a sum of positive squares in 4 ways, for example, as 675684 + 133956 = 822^2 + 366^2 .

It is a congruent number.

It is an unprimeable number.

809640 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4594 + ... + 4766.

2⁸⁰⁹⁶⁴⁰ 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 809640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1425060).

809640 is an abundant number, since it is smaller than the sum of its proper divisors (2040480).

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

809640 is a wasteful number, since it uses less digits than its factorization.

809640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203 (or 196 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 809640 is about 899.7999777728. The cubic root of 809640 is about 93.2031632099.

The spelling of 809640 in words is "eight hundred nine thousand, six hundred forty".