821806128 has 320 divisors, whose sum is σ = 2834818560. Its totient is φ = 224640000.

The previous prime is 821806039. The next prime is 821806171. The reversal of 821806128 is 821608128.

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

It is a junction number, because it is equal to n+sod(n) for n = 821806092 and 821806101.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3274003 + ... + 3274253.

It is an arithmetic number, because the mean of its divisors is an integer number (8858808).

Almost surely, 2^821806128 is an apocalyptic number.

821806128 is a gapful number since it is divisible by the number (88) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821806128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1417409280).

821806128 is an abundant number, since it is smaller than the sum of its proper divisors (2013012432).

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

821806128 is a wasteful number, since it uses less digits than its factorization.

821806128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345 (or 333 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 36.

The square root of 821806128 is about 28667.1611430222. The cubic root of 821806128 is about 936.6768608429.

The spelling of 821806128 in words is "eight hundred twenty-one million, eight hundred six thousand, one hundred twenty-eight".