81717804818 has 16 divisors (see below), whose sum is σ = 132019856640. Its totient is φ = 37711860816.

The previous prime is 81717804811. The next prime is 81717804821. The reversal of 81717804818 is 81840871718.

It is a self number, because there is not a number n which added to its sum of digits gives 81717804818.

It is not an unprimeable number, because it can be changed into a prime (81717804811) 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, 85343 + ... + 413181.

It is an arithmetic number, because the mean of its divisors is an integer number (8251241040).

Almost surely, 2^81717804818 is an apocalyptic number.

81717804818 is a deficient number, since it is larger than the sum of its proper divisors (50302051822).

81717804818 is a wasteful number, since it uses less digits than its factorization.

81717804818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337441.

The product of its (nonzero) digits is 802816, while the sum is 53.

The spelling of 81717804818 in words is "eighty-one billion, seven hundred seventeen million, eight hundred four thousand, eight hundred eighteen".