81216 has 56 divisors (see below), whose sum is σ = 243840. Its totient is φ = 26496.

The previous prime is 81203. The next prime is 81223. The reversal of 81216 is 61218.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is an unprimeable number.

81216 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1705 + ... + 1751.

2⁸¹²¹⁶ 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 81216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121920).

81216 is an abundant number, since it is smaller than the sum of its proper divisors (162624).

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

81216 is a wasteful number, since it uses less digits than its factorization.

81216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68 (or 52 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 81216 is about 284.9842100889. The cubic root of 81216 is about 43.3059129617.

It can be divided in two parts, 812 and 16, that added together give a palindrome (828).

The spelling of 81216 in words is "eighty-one thousand, two hundred sixteen".