816521308213464 has 448 divisors, whose sum is σ = 2711725655040000. Its totient is φ = 225452008730880.

The previous prime is 816521308213451. The next prime is 816521308213477. The reversal of 816521308213464 is 464312803125618.

816521308213464 is a `hidden beast` number, since 8 + 1 + 6 + 5 + 213 + 0 + 82 + 1 + 346 + 4 = 666.

816521308213464 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (816521308213451) and next prime (816521308213477).

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

It is a self number, because there is not a number n which added to its sum of digits gives 816521308213464.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 909477462 + ... + 910374810.

Almost surely, 2^{816521308213464} is an apocalyptic number.

816521308213464 is a gapful number since it is divisible by the number (84) 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 816521308213464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1355862827520000).

816521308213464 is an abundant number, since it is smaller than the sum of its proper divisors (1895204346826536).

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

816521308213464 is a wasteful number, since it uses less digits than its factorization.

816521308213464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 898130 (or 898111 counting only the distinct ones).

The product of its (nonzero) digits is 6635520, while the sum is 54.

The spelling of 816521308213464 in words is "eight hundred sixteen trillion, five hundred twenty-one billion, three hundred eight million, two hundred thirteen thousand, four hundred sixty-four".