6821664659824 has 320 divisors, whose sum is σ = 17154502041600. Its totient is φ = 2561178009600.

The previous prime is 6821664659819. The next prime is 6821664659851. The reversal of 6821664659824 is 4289564661286.

It is a self number, because there is not a number n which added to its sum of digits gives 6821664659824.

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 63 ways as a sum of consecutive naturals, for example, 185549604 + ... + 185586364.

It is an arithmetic number, because the mean of its divisors is an integer number (53607818880).

Almost surely, 2^{6821664659824} 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 6821664659824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8577251020800).

6821664659824 is an abundant number, since it is smaller than the sum of its proper divisors (10332837381776).

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

6821664659824 is a wasteful number, since it uses less digits than its factorization.

6821664659824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36952 (or 36946 counting only the distinct ones).

The product of its digits is 238878720, while the sum is 67.

The spelling of 6821664659824 in words is "six trillion, eight hundred twenty-one billion, six hundred sixty-four million, six hundred fifty-nine thousand, eight hundred twenty-four".