81868660129 has 9 divisors (see below), whose sum is σ = 86972913651. Its totient is φ = 77048278560.

The previous prime is 81868660109. The next prime is 81868660141. The reversal of 81868660129 is 92106686818.

The square root of 81868660129 is 286127.

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

It can be written as a sum of positive squares in only one way, i.e., 63738576225 + 18130083904 = 252465^2 + 134648^2 .

It is not a de Polignac number, because 81868660129 - 2³³ = 73278725537 is a prime.

It is a super-2 number, since 2×81868660129² (a number of 23 digits) contains 22 as substring.

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 81868660129.

It is not an unprimeable number, because it can be changed into a prime (81868660109) 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, 4855744 + ... + 4872574.

Almost surely, 2^81868660129 is an apocalyptic number.

81868660129 is the 286127-th square number.

81868660129 is the 143064-th centered octagonal number.

It is an amenable number.

81868660129 is a deficient number, since it is larger than the sum of its proper divisors (5104253522).

81868660129 is an frugal number, since it uses more digits than its factorization.

81868660129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33696 (or 16848 counting only the distinct ones).

The product of its (nonzero) digits is 1990656, while the sum is 55.

The spelling of 81868660129 in words is "eighty-one billion, eight hundred sixty-eight million, six hundred sixty thousand, one hundred twenty-nine".