81218138241 has 8 divisors (see below), whose sum is σ = 110932091424. Its totient is φ = 52824805280.

The previous prime is 81218138203. The next prime is 81218138257. The reversal of 81218138241 is 14283181218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81218138241 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81218138241.

It is not an unprimeable number, because it can be changed into a prime (81218138291) 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 7 ways as a sum of consecutive naturals, for example, 330154911 + ... + 330155156.

It is an arithmetic number, because the mean of its divisors is an integer number (13866511428).

Almost surely, 2^81218138241 is an apocalyptic number.

It is an amenable number.

81218138241 is a deficient number, since it is larger than the sum of its proper divisors (29713953183).

81218138241 is a wasteful number, since it uses less digits than its factorization.

81218138241 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 660310111.

The product of its digits is 24576, while the sum is 39.

The spelling of 81218138241 in words is "eighty-one billion, two hundred eighteen million, one hundred thirty-eight thousand, two hundred forty-one".