809810820 has 216 divisors, whose sum is σ = 3040704576. Its totient is φ = 170816256.

The previous prime is 809810791. The next prime is 809810849. The reversal of 809810820 is 28018908.

It is an interprime number because it is at equal distance from previous prime (809810791) and next prime (809810849).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 211039 + ... + 214841.

It is an arithmetic number, because the mean of its divisors is an integer number (14077336).

Almost surely, 2^809810820 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 809810820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1520352288).

809810820 is an abundant number, since it is smaller than the sum of its proper divisors (2230893756).

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

809810820 is a wasteful number, since it uses less digits than its factorization.

809810820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3851 (or 3833 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 36.

The square root of 809810820 is about 28457.1751936133. The cubic root of 809810820 is about 932.0971749942.

The spelling of 809810820 in words is "eight hundred nine million, eight hundred ten thousand, eight hundred twenty".