81704784818 has 4 divisors (see below), whose sum is σ = 122557177230. Its totient is φ = 40852392408.

The previous prime is 81704784797. The next prime is 81704784823. The reversal of 81704784818 is 81848740718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 77015685289 + 4689099529 = 277517^2 + 68477^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20426196203 + ... + 20426196206.

Almost surely, 2^81704784818 is an apocalyptic number.

81704784818 is a deficient number, since it is larger than the sum of its proper divisors (40852392412).

81704784818 is a wasteful number, since it uses less digits than its factorization.

81704784818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40852392411.

The product of its (nonzero) digits is 3211264, while the sum is 56.

The spelling of 81704784818 in words is "eighty-one billion, seven hundred four million, seven hundred eighty-four thousand, eight hundred eighteen".