821968566 has 8 divisors (see below), whose sum is σ = 1643937144. Its totient is φ = 273989520.

The previous prime is 821968559. The next prime is 821968601. The reversal of 821968566 is 665869128.

It is a sphenic number, since it is the product of 3 distinct primes.

821968566 is an admirable number.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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 3 ways as a sum of consecutive naturals, for example, 68497375 + ... + 68497386.

It is an arithmetic number, because the mean of its divisors is an integer number (205492143).

Almost surely, 2^821968566 is an apocalyptic number.

821968566 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

821968566 is a wasteful number, since it uses less digits than its factorization.

821968566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136994766.

The product of its digits is 1244160, while the sum is 51.

The square root of 821968566 is about 28669.9941750953. The cubic root of 821968566 is about 936.7385712176.

The spelling of 821968566 in words is "eight hundred twenty-one million, nine hundred sixty-eight thousand, five hundred sixty-six".