81441135569664 has 864 divisors, whose sum is σ = 264372098099200. Its totient is φ = 24856274386944.

The previous prime is 81441135569617. The next prime is 81441135569701. The reversal of 81441135569664 is 46696553114418.

81441135569664 is a `hidden beast` number, since 8 + 1 + 4 + 4 + 1 + 1 + 3 + 5 + 569 + 6 + 64 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 74511559902 + ... + 74511560994.

Almost surely, 2^{81441135569664} 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 81441135569664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132186049049600).

81441135569664 is an abundant number, since it is smaller than the sum of its proper divisors (182930962529536).

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

81441135569664 is a wasteful number, since it uses less digits than its factorization.

81441135569664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1799 (or 1773 counting only the distinct ones).

The product of its digits is 74649600, while the sum is 63.

The spelling of 81441135569664 in words is "eighty-one trillion, four hundred forty-one billion, one hundred thirty-five million, five hundred sixty-nine thousand, six hundred sixty-four".