821773812 has 72 divisors (see below), whose sum is σ = 2107395360. Its totient is φ = 248890880.

The previous prime is 821773801. The next prime is 821773819. The reversal of 821773812 is 218377128.

It is a super-2 number, since 2×821773812² = 1350624396178022688, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821773819) 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 23 ways as a sum of consecutive naturals, for example, 96487 + ... + 104657.

It is an arithmetic number, because the mean of its divisors is an integer number (29269380).

Almost surely, 2^821773812 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 821773812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1053697680).

821773812 is an abundant number, since it is smaller than the sum of its proper divisors (1285621548).

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

821773812 is a wasteful number, since it uses less digits than its factorization.

821773812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8241 (or 8222 counting only the distinct ones).

The product of its digits is 37632, while the sum is 39.

The square root of 821773812 is about 28666.5974960406. The cubic root of 821773812 is about 936.6645829892.

The spelling of 821773812 in words is "eight hundred twenty-one million, seven hundred seventy-three thousand, eight hundred twelve".