81299194568064 has 288 divisors, whose sum is σ = 257319097373520. Its totient is φ = 24619751270400.

The previous prime is 81299194568017. The next prime is 81299194568087. The reversal of 81299194568064 is 46086549199218.

81299194568064 is a `hidden beast` number, since 8 + 1 + 2 + 9 + 91 + 9 + 456 + 80 + 6 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 81299194567983 and 81299194568001.

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 35 ways as a sum of consecutive naturals, for example, 210428314 + ... + 210814310.

Almost surely, 2^{81299194568064} 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 81299194568064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128659548686760).

81299194568064 is an abundant number, since it is smaller than the sum of its proper divisors (176019902805456).

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

81299194568064 is a wasteful number, since it uses less digits than its factorization.

81299194568064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 387550 (or 387524 counting only the distinct ones).

The product of its (nonzero) digits is 268738560, while the sum is 72.

The spelling of 81299194568064 in words is "eighty-one trillion, two hundred ninety-nine billion, one hundred ninety-four million, five hundred sixty-eight thousand, sixty-four".