12181806 has 128 divisors (see below), whose sum is σ = 34728960. Its totient is φ = 3079296.

The previous prime is 12181781. The next prime is 12181817. The reversal of 12181806 is 60818121.

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 12181806.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 181785 + ... + 181851.

It is an arithmetic number, because the mean of its divisors is an integer number (271320).

Almost surely, 2^12181806 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 12181806, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17364480).

12181806 is an abundant number, since it is smaller than the sum of its proper divisors (22547154).

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

12181806 is a wasteful number, since it uses less digits than its factorization.

12181806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135 (or 129 counting only the distinct ones).

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

The square root of 12181806 is about 3490.2444040497. The cubic root of 12181806 is about 230.0932577080.

Adding to 12181806 its reverse (60818121), we get a palindrome (72999927).

The spelling of 12181806 in words is "twelve million, one hundred eighty-one thousand, eight hundred six".