821664903892 has 144 divisors (see below), whose sum is σ = 1789818750720. Its totient is φ = 328476556800.

The previous prime is 821664903869. The next prime is 821664903901. The reversal of 821664903892 is 298309466128.

It is a Harshad number since it is a multiple of its sum of digits (58).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 23986417 + ... + 24020647.

It is an arithmetic number, because the mean of its divisors is an integer number (12429296880).

Almost surely, 2^821664903892 is an apocalyptic number.

821664903892 is a gapful number since it is divisible by the number (82) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821664903892, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (894909375360).

821664903892 is an abundant number, since it is smaller than the sum of its proper divisors (968153846828).

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

821664903892 is a wasteful number, since it uses less digits than its factorization.

821664903892 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34422 (or 34413 counting only the distinct ones).

The product of its (nonzero) digits is 8957952, while the sum is 58.

The spelling of 821664903892 in words is "eight hundred twenty-one billion, six hundred sixty-four million, nine hundred three thousand, eight hundred ninety-two".