6821815668 has 96 divisors (see below), whose sum is σ = 16823009280. Its totient is φ = 2148975360.

The previous prime is 6821815657. The next prime is 6821815687. The reversal of 6821815668 is 8665181286.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 6821815668.

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 in 31 ways as a sum of consecutive naturals, for example, 2685543 + ... + 2688081.

It is an arithmetic number, because the mean of its divisors is an integer number (175239680).

Almost surely, 2^6821815668 is an apocalyptic number.

It is an amenable number.

6821815668 is an abundant number, since it is smaller than the sum of its proper divisors (10001193612).

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

6821815668 is a wasteful number, since it uses less digits than its factorization.

6821815668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2757 (or 2755 counting only the distinct ones).

The product of its digits is 1105920, while the sum is 51.

The square root of 6821815668 is about 82594.2835067900. The cubic root of 6821815668 is about 1896.5603203822.

The spelling of 6821815668 in words is "six billion, eight hundred twenty-one million, eight hundred fifteen thousand, six hundred sixty-eight".