81806581613628 has 72 divisors (see below), whose sum is σ = 217694055488000. Its totient is φ = 25831097129376.

The previous prime is 81806581613599. The next prime is 81806581613639. The reversal of 81806581613628 is 82631618560818.

81806581613628 is a `hidden beast` number, since 8 + 1 + 8 + 0 + 6 + 5 + 8 + 1 + 613 + 6 + 2 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 986325 + ... + 12829107.

Almost surely, 2^{81806581613628} is an apocalyptic number.

It is an amenable number.

81806581613628 is an abundant number, since it is smaller than the sum of its proper divisors (135887473874372).

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

81806581613628 is a wasteful number, since it uses less digits than its factorization.

81806581613628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11852911 (or 11852906 counting only the distinct ones).

The product of its (nonzero) digits is 26542080, while the sum is 63.

The spelling of 81806581613628 in words is "eighty-one trillion, eight hundred six billion, five hundred eighty-one million, six hundred thirteen thousand, six hundred twenty-eight".