72181812 has 48 divisors (see below), whose sum is σ = 178516800. Its totient is φ = 22659840.

The previous prime is 72181789. The next prime is 72181819. The reversal of 72181812 is 21818127.

It is a happy number.

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

It is a self number, because there is not a number n which added to its sum of digits gives 72181812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72181819) 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 15 ways as a sum of consecutive naturals, for example, 11739 + ... + 16797.

It is an arithmetic number, because the mean of its divisors is an integer number (3719100).

Almost surely, 2^72181812 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 72181812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (89258400).

72181812 is an abundant number, since it is smaller than the sum of its proper divisors (106334988).

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

72181812 is a wasteful number, since it uses less digits than its factorization.

72181812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5136 (or 5134 counting only the distinct ones).

The product of its digits is 1792, while the sum is 30.

The square root of 72181812 is about 8495.9879943418. The cubic root of 72181812 is about 416.3666408324.

Adding to 72181812 its reverse (21818127), we get a palindrome (93999939).

The spelling of 72181812 in words is "seventy-two million, one hundred eighty-one thousand, eight hundred twelve".