821855966 has 4 divisors (see below), whose sum is σ = 1232783952. Its totient is φ = 410927982.

The previous prime is 821855933. The next prime is 821855971. The reversal of 821855966 is 669558128.

It is a semiprime because it is the product of two primes.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 205463990 + ... + 205463993.

It is an arithmetic number, because the mean of its divisors is an integer number (308195988).

Almost surely, 2^821855966 is an apocalyptic number.

821855966 is a deficient number, since it is larger than the sum of its proper divisors (410927986).

821855966 is a wasteful number, since it uses less digits than its factorization.

821855966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410927985.

The product of its digits is 1036800, while the sum is 50.

The square root of 821855966 is about 28668.0303822917. The cubic root of 821855966 is about 936.6957952185.

The spelling of 821855966 in words is "eight hundred twenty-one million, eight hundred fifty-five thousand, nine hundred sixty-six".