81835731561 has 8 divisors (see below), whose sum is σ = 109159575264. Its totient is φ = 54534521120.

The previous prime is 81835731557. The next prime is 81835731569. The reversal of 81835731561 is 16513753818.

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

It is a cyclic number.

It is not a de Polignac number, because 81835731561 - 2² = 81835731557 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81835731561.

It is not an unprimeable number, because it can be changed into a prime (81835731569) 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, 5649876 + ... + 5664341.

It is an arithmetic number, because the mean of its divisors is an integer number (13644946908).

Almost surely, 2^81835731561 is an apocalyptic number.

It is an amenable number.

81835731561 is a deficient number, since it is larger than the sum of its proper divisors (27323843703).

81835731561 is a wasteful number, since it uses less digits than its factorization.

81835731561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11316631.

The product of its digits is 604800, while the sum is 48.

The spelling of 81835731561 in words is "eighty-one billion, eight hundred thirty-five million, seven hundred thirty-one thousand, five hundred sixty-one".