817196821056 has 1512 divisors, whose sum is σ = 3212319569760. Its totient is φ = 202937011200.

The previous prime is 817196821031. The next prime is 817196821069. The reversal of 817196821056 is 650128691718.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (1512).

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

It is a junction number, because it is equal to n+sod(n) for n = 817196820993 and 817196821011.

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 215 ways as a sum of consecutive naturals, for example, 9845744791 + ... + 9845744873.

It is an arithmetic number, because the mean of its divisors is an integer number (2124549980).

Almost surely, 2^817196821056 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 817196821056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1606159784880).

817196821056 is an abundant number, since it is smaller than the sum of its proper divisors (2395122748704).

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

817196821056 is a wasteful number, since it uses less digits than its factorization.

817196821056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 1451520, while the sum is 54.

The spelling of 817196821056 in words is "eight hundred seventeen billion, one hundred ninety-six million, eight hundred twenty-one thousand, fifty-six".