821800188 has 96 divisors (see below), whose sum is σ = 2330173440. Its totient is φ = 248400000.

The previous prime is 821800169. The next prime is 821800211. The reversal of 821800188 is 881008128.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 713413 + ... + 714563.

It is an arithmetic number, because the mean of its divisors is an integer number (24272640).

Almost surely, 2^821800188 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 821800188, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1165086720).

821800188 is an abundant number, since it is smaller than the sum of its proper divisors (1508373252).

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

821800188 is a wasteful number, since it uses less digits than its factorization.

821800188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1776 (or 1768 counting only the distinct ones).

The product of its (nonzero) digits is 8192, while the sum is 36.

The square root of 821800188 is about 28667.0575399709. The cubic root of 821800188 is about 936.6746040763.

The spelling of 821800188 in words is "eight hundred twenty-one million, eight hundred thousand, one hundred eighty-eight".