81806103774561 has 8 divisors (see below), whose sum is σ = 109468576893184. Its totient is φ = 54340516586160.

The previous prime is 81806103774533. The next prime is 81806103774613. The reversal of 81806103774561 is 16547730160818.

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

It is not a de Polignac number, because 81806103774561 - 2¹⁹ = 81806103250273 is a prime.

It is a super-2 number, since 2×81806103774561² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81806103774511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49221481585 + ... + 49221483246.

It is an arithmetic number, because the mean of its divisors is an integer number (13683572111648).

Almost surely, 2^{81806103774561} is an apocalyptic number.

It is an amenable number.

81806103774561 is a deficient number, since it is larger than the sum of its proper divisors (27662473118623).

81806103774561 is a wasteful number, since it uses less digits than its factorization.

81806103774561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98442965111.

The product of its (nonzero) digits is 6773760, while the sum is 57.

The spelling of 81806103774561 in words is "eighty-one trillion, eight hundred six billion, one hundred three million, seven hundred seventy-four thousand, five hundred sixty-one".