821905872 has 60 divisors (see below), whose sum is σ = 2160293280. Its totient is φ = 269270336.

The previous prime is 821905859. The next prime is 821905879. The reversal of 821905872 is 278509128.

821905872 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821905879) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 164629 + ... + 169547.

It is an arithmetic number, because the mean of its divisors is an integer number (36004888).

Almost surely, 2^821905872 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 821905872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1080146640).

821905872 is an abundant number, since it is smaller than the sum of its proper divisors (1338387408).

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

821905872 is a wasteful number, since it uses less digits than its factorization.

821905872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5048 (or 4983 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 42.

The square root of 821905872 is about 28668.9007811601. The cubic root of 821905872 is about 936.7147546616.

The spelling of 821905872 in words is "eight hundred twenty-one million, nine hundred five thousand, eight hundred seventy-two".