81185033681 has 8 divisors (see below), whose sum is σ = 81558758400. Its totient is φ = 80811395712.

The previous prime is 81185033659. The next prime is 81185033687. The reversal of 81185033681 is 18633058118.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81185033681 is a prime.

It is a super-2 number, since 2×81185033681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81185033687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2549345 + ... + 2580993.

It is an arithmetic number, because the mean of its divisors is an integer number (10194844800).

Almost surely, 2^81185033681 is an apocalyptic number.

It is an amenable number.

81185033681 is a deficient number, since it is larger than the sum of its proper divisors (373724719).

81185033681 is a wasteful number, since it uses less digits than its factorization.

81185033681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43375.

The product of its (nonzero) digits is 138240, while the sum is 44.

The spelling of 81185033681 in words is "eighty-one billion, one hundred eighty-five million, thirty-three thousand, six hundred eighty-one".