810305821 has 6 divisors (see below), whose sum is σ = 877431930. Its totient is φ = 747974448.

The previous prime is 810305819. The next prime is 810305827. The reversal of 810305821 is 128503018.

It can be written as a sum of positive squares in 3 ways, for example, as 10208025 + 800097796 = 3195^2 + 28286^2 .

It is not a de Polignac number, because 810305821 - 2¹ = 810305819 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 810305821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (810305827) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2397186 + ... + 2397523.

It is an arithmetic number, because the mean of its divisors is an integer number (146238655).

Almost surely, 2^810305821 is an apocalyptic number.

It is an amenable number.

810305821 is a deficient number, since it is larger than the sum of its proper divisors (67126109).

810305821 is a wasteful number, since it uses less digits than its factorization.

810305821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4794735 (or 4794722 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 810305821 is about 28465.8711617965. The cubic root of 810305821 is about 932.2870526979.

Adding to 810305821 its reverse (128503018), we get a palindrome (938808839).

The spelling of 810305821 in words is "eight hundred ten million, three hundred five thousand, eight hundred twenty-one".