81138144318 has 64 divisors (see below), whose sum is σ = 203158264320. Its totient is φ = 20987366400.

The previous prime is 81138144251. The next prime is 81138144379. The reversal of 81138144318 is 81344183118.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 81138144318.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 253023 + ... + 475706.

It is an arithmetic number, because the mean of its divisors is an integer number (3174347880).

Almost surely, 2^81138144318 is an apocalyptic number.

81138144318 is an abundant number, since it is smaller than the sum of its proper divisors (122020120002).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81138144318 is a wasteful number, since it uses less digits than its factorization.

81138144318 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 728993.

The product of its digits is 73728, while the sum is 42.

It can be divided in two parts, 81138 and 144318, that added together give a triangular number (225456 = T₆₇₁).

The spelling of 81138144318 in words is "eighty-one billion, one hundred thirty-eight million, one hundred forty-four thousand, three hundred eighteen".