81171216 has 60 divisors (see below), whose sum is σ = 259622272. Its totient is φ = 23191488.

The previous prime is 81171199. The next prime is 81171217. The reversal of 81171216 is 61217118.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 81171216.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81171217) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 39256 + ... + 41271.

Almost surely, 2^81171216 is an apocalyptic number.

It is an amenable number.

81171216 is an abundant number, since it is smaller than the sum of its proper divisors (178451056).

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

81171216 is a wasteful number, since it uses less digits than its factorization.

81171216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80548 (or 80539 counting only the distinct ones).

The product of its digits is 672, while the sum is 27.

The square root of 81171216 is about 9009.5069787420. The cubic root of 81171216 is about 432.9795160515.

It can be divided in two parts, 811 and 71216, that added together give a palindrome (72027).

The spelling of 81171216 in words is "eighty-one million, one hundred seventy-one thousand, two hundred sixteen".