81359876840841 has 63 divisors (see below), whose sum is σ = 125383869349221. Its totient is φ = 52768129225824.

The previous prime is 81359876840839. The next prime is 81359876840849. The reversal of 81359876840841 is 14804867895318.

It is a happy number.

The square root of 81359876840841 is 9019971.

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

81359876840841 is a `hidden beast` number, since 8 + 1 + 35 + 98 + 7 + 68 + 408 + 41 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 70588982975625 + 10770893865216 = 8401725^2 + 3281904^2 .

It is not a de Polignac number, because 81359876840841 - 2¹ = 81359876840839 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81359876840841.

It is not an unprimeable number, because it can be changed into a prime (81359876840849) by changing a digit.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 9010946515 + ... + 9010955543.

Almost surely, 2^{81359876840841} is an apocalyptic number.

81359876840841 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

81359876840841 is the 9019971-st square number.

81359876840841 is the 4509986-th centered octagonal number.

It is an amenable number.

81359876840841 is a deficient number, since it is larger than the sum of its proper divisors (44023992508380).

81359876840841 is an frugal number, since it uses more digits than its factorization.

81359876840841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18150 (or 9069 counting only the distinct ones).

The product of its (nonzero) digits is 371589120, while the sum is 72.

The spelling of 81359876840841 in words is "eighty-one trillion, three hundred fifty-nine billion, eight hundred seventy-six million, eight hundred forty thousand, eight hundred forty-one".