821808128 has 44 divisors (see below), whose sum is σ = 1652665920. Its totient is φ = 408440832.

The previous prime is 821808103. The next prime is 821808133.

821808128 is nontrivially palindromic in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 821808091 and 821808100.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 174833 + ... + 179471.

Almost surely, 2^821808128 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 821808128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (826332960).

821808128 is an abundant number, since it is smaller than the sum of its proper divisors (830857792).

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

821808128 is a wasteful number, since it uses less digits than its factorization.

821808128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4832 (or 4814 counting only the distinct ones).

The product of its (nonzero) digits is 16384, while the sum is 38.

The square root of 821808128 is about 28667.1960261202. The cubic root of 821808128 is about 936.6776206946.

The spelling of 821808128 in words is "eight hundred twenty-one million, eight hundred eight thousand, one hundred twenty-eight".