81766533566718 has 576 divisors, whose sum is σ = 246420773254656. Its totient is φ = 19053212428800.

The previous prime is 81766533566717. The next prime is 81766533566743.

It is a happy number.

81766533566718 is a `hidden beast` number, since 8 + 1 + 7 + 6 + 6 + 53 + 3 + 566 + 7 + 1 + 8 = 666.

81766533566718 is nontrivially palindromic in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81766533566713) by changing a digit.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 7120653805 + ... + 7120665287.

It is an arithmetic number, because the mean of its divisors is an integer number (427813842456).

Almost surely, 2^{81766533566718} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81766533566718, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123210386627328).

81766533566718 is an abundant number, since it is smaller than the sum of its proper divisors (164654239687938).

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

81766533566718 is a wasteful number, since it uses less digits than its factorization.

81766533566718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12541 (or 12527 counting only the distinct ones).

The product of its digits is 914457600, while the sum is 72.

The spelling of 81766533566718 in words is "eighty-one trillion, seven hundred sixty-six billion, five hundred thirty-three million, five hundred sixty-six thousand, seven hundred eighteen".