81804742805 has 16 divisors (see below), whose sum is σ = 99278799984. Its totient is φ = 64705904640.

The previous prime is 81804742787. The next prime is 81804742819. The reversal of 81804742805 is 50824740818.

It can be written as a sum of positive squares in 8 ways, for example, as 11240664484 + 70564078321 = 106022^2 + 265639^2 .

It is not a de Polignac number, because 81804742805 - 2²⁶ = 81737633941 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81804742805.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 104684 + ... + 417813.

It is an arithmetic number, because the mean of its divisors is an integer number (6204924999).

Almost surely, 2^81804742805 is an apocalyptic number.

It is an amenable number.

81804742805 is a deficient number, since it is larger than the sum of its proper divisors (17474057179).

81804742805 is a wasteful number, since it uses less digits than its factorization.

81804742805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 522856.

The product of its (nonzero) digits is 573440, while the sum is 47.

The spelling of 81804742805 in words is "eighty-one billion, eight hundred four million, seven hundred forty-two thousand, eight hundred five".