821920866 has 32 divisors (see below), whose sum is σ = 1807964928. Its totient is φ = 247516800.

The previous prime is 821920861. The next prime is 821920889. The reversal of 821920866 is 668029128.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (821920861) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 108435 + ... + 115766.

It is an arithmetic number, because the mean of its divisors is an integer number (56498904).

Almost surely, 2^821920866 is an apocalyptic number.

821920866 is an abundant number, since it is smaller than the sum of its proper divisors (986044062).

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

821920866 is a wasteful number, since it uses less digits than its factorization.

821920866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224266.

The product of its (nonzero) digits is 82944, while the sum is 42.

The square root of 821920866 is about 28669.1622828432. The cubic root of 821920866 is about 936.7204507784.

The spelling of 821920866 in words is "eight hundred twenty-one million, nine hundred twenty thousand, eight hundred sixty-six".