821719866 has 64 divisors (see below), whose sum is σ = 1895731200. Its totient is φ = 234835200.

The previous prime is 821719861. The next prime is 821719891. The reversal of 821719866 is 668917128.

It is not an unprimeable number, because it can be changed into a prime (821719861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 300855 + ... + 303573.

It is an arithmetic number, because the mean of its divisors is an integer number (29620800).

Almost surely, 2^821719866 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821719866, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (947865600).

821719866 is an abundant number, since it is smaller than the sum of its proper divisors (1074011334).

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

821719866 is a wasteful number, since it uses less digits than its factorization.

821719866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2995.

The product of its digits is 290304, while the sum is 48.

The square root of 821719866 is about 28665.6565597232. The cubic root of 821719866 is about 936.6440865085.

The spelling of 821719866 in words is "eight hundred twenty-one million, seven hundred nineteen thousand, eight hundred sixty-six".