81081216 has 128 divisors (see below), whose sum is σ = 247860000. Its totient is φ = 26062848.

The previous prime is 81081199. The next prime is 81081241. The reversal of 81081216 is 61218018.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 81081216.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 99820 + ... + 100628.

Almost surely, 2^81081216 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81081216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123930000).

81081216 is an abundant number, since it is smaller than the sum of its proper divisors (166778784).

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

81081216 is a wasteful number, since it uses less digits than its factorization.

81081216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 861 (or 843 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 27.

The square root of 81081216 is about 9004.5108695587. The cubic root of 81081216 is about 432.8194323443.

The spelling of 81081216 in words is "eighty-one million, eighty-one thousand, two hundred sixteen".