81218318272 has 224 divisors, whose sum is σ = 204743669760. Its totient is φ = 31108423680.

The previous prime is 81218318263. The next prime is 81218318273. The reversal of 81218318272 is 27281381218.

It is a tau number, because it is divible by the number of its divisors (224).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81218318273) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 33189753 + ... + 33192199.

It is an arithmetic number, because the mean of its divisors is an integer number (914034240).

Almost surely, 2^81218318272 is an apocalyptic number.

81218318272 is a gapful number since it is divisible by the number (82) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81218318272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102371834880).

81218318272 is an abundant number, since it is smaller than the sum of its proper divisors (123525351488).

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

81218318272 is a wasteful number, since it uses less digits than its factorization.

81218318272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2659 (or 2649 counting only the distinct ones).

The product of its digits is 86016, while the sum is 43.

The spelling of 81218318272 in words is "eighty-one billion, two hundred eighteen million, three hundred eighteen thousand, two hundred seventy-two".