821312515728 has 480 divisors, whose sum is σ = 2620632268800. Its totient is φ = 248008739328.

The previous prime is 821312515721. The next prime is 821312515769. The reversal of 821312515728 is 827515213128.

821312515728 is a `hidden beast` number, since 8 + 2 + 13 + 12 + 51 + 572 + 8 = 666.

821312515728 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (821312515721) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 229223025 + ... + 229226607.

It is an arithmetic number, because the mean of its divisors is an integer number (5459650560).

Almost surely, 2^821312515728 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 821312515728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1310316134400).

821312515728 is an abundant number, since it is smaller than the sum of its proper divisors (1799319753072).

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

821312515728 is a wasteful number, since it uses less digits than its factorization.

821312515728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3761 (or 3743 counting only the distinct ones).

The product of its digits is 268800, while the sum is 45.

The spelling of 821312515728 in words is "eight hundred twenty-one billion, three hundred twelve million, five hundred fifteen thousand, seven hundred twenty-eight".