81218884129 has 2 divisors, whose sum is σ = 81218884130. Its totient is φ = 81218884128.

The previous prime is 81218884111. The next prime is 81218884193. The reversal of 81218884129 is 92148881218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48048640000 + 33170244129 = 219200^2 + 182127^2 .

It is a cyclic number.

It is not a de Polignac number, because 81218884129 - 2¹¹ = 81218882081 is a prime.

It is not a weakly prime, because it can be changed into another prime (81218884729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40609442064 + 40609442065.

It is an arithmetic number, because the mean of its divisors is an integer number (40609442065).

Almost surely, 2^81218884129 is an apocalyptic number.

It is an amenable number.

81218884129 is a deficient number, since it is larger than the sum of its proper divisors (1).

81218884129 is an equidigital number, since it uses as much as digits as its factorization.

81218884129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 589824, while the sum is 52.

The spelling of 81218884129 in words is "eighty-one billion, two hundred eighteen million, eight hundred eighty-four thousand, one hundred twenty-nine".