821781282816 has 1200 divisors, whose sum is σ = 2930785334400. Its totient is φ = 227030335488.

The previous prime is 821781282811. The next prime is 821781282851. The reversal of 821781282816 is 618282187128.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821781282811) by changing a digit.

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 79 ways as a sum of consecutive naturals, for example, 7539277770 + ... + 7539277878.

It is an arithmetic number, because the mean of its divisors is an integer number (2442321112).

Almost surely, 2^821781282816 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 821781282816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1465392667200).

821781282816 is an abundant number, since it is smaller than the sum of its proper divisors (2109004051584).

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

821781282816 is a wasteful number, since it uses less digits than its factorization.

821781282816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204 (or 169 counting only the distinct ones).

The product of its digits is 1376256, while the sum is 54.

The spelling of 821781282816 in words is "eight hundred twenty-one billion, seven hundred eighty-one million, two hundred eighty-two thousand, eight hundred sixteen".