821800 has 48 divisors (see below), whose sum is σ = 2187360. Its totient is φ = 281280.

The previous prime is 821771. The next prime is 821801. The reversal of 821800 is 8128.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (821801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1107 + ... + 1693.

It is an arithmetic number, because the mean of its divisors is an integer number (45570).

2⁸²¹⁸⁰⁰ 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 821800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1093680).

821800 is an abundant number, since it is smaller than the sum of its proper divisors (1365560).

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

821800 is a wasteful number, since it uses less digits than its factorization.

821800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 610 (or 601 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 821800 is about 906.5318527222. The cubic root of 821800 is about 93.6674532650.

Adding to 821800 its reverse (8128), we get a palindrome (829928).

The spelling of 821800 in words is "eight hundred twenty-one thousand, eight hundred".