816585820 has 48 divisors (see below), whose sum is σ = 1820780640. Its totient is φ = 306561024.

The previous prime is 816585779. The next prime is 816585829. The reversal of 816585820 is 28585618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816585829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 125692 + ... + 132028.

It is an arithmetic number, because the mean of its divisors is an integer number (37932930).

Almost surely, 2^816585820 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 816585820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (910390320).

816585820 is an abundant number, since it is smaller than the sum of its proper divisors (1004194820).

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

816585820 is a wasteful number, since it uses less digits than its factorization.

816585820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6742 (or 6740 counting only the distinct ones).

The product of its (nonzero) digits is 153600, while the sum is 43.

The square root of 816585820 is about 28575.9657754554. The cubic root of 816585820 is about 934.6893150226.

It can be divided in two parts, 81658 and 5820, that added together give a palindrome (87478).

The spelling of 816585820 in words is "eight hundred sixteen million, five hundred eighty-five thousand, eight hundred twenty".