81686784481 has 9 divisors (see below), whose sum is σ = 82039557873. Its totient is φ = 81335525220.

The previous prime is 81686784467. The next prime is 81686784511. The reversal of 81686784481 is 18448768618.

The square root of 81686784481 is 285809.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 81686784481 - 2⁷ = 81686784353 is a prime.

It is a super-2 number, since 2×81686784481² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81686754481) 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 8 ways as a sum of consecutive naturals, for example, 88886140 + ... + 88887058.

Almost surely, 2^81686784481 is an apocalyptic number.

81686784481 is the 285809-th square number.

81686784481 is the 142905-th centered octagonal number.

It is an amenable number.

81686784481 is a deficient number, since it is larger than the sum of its proper divisors (352773392).

81686784481 is an frugal number, since it uses more digits than its factorization.

81686784481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2460 (or 1230 counting only the distinct ones).

The product of its digits is 16515072, while the sum is 61.

The spelling of 81686784481 in words is "eighty-one billion, six hundred eighty-six million, seven hundred eighty-four thousand, four hundred eighty-one".