12181813 has 4 divisors (see below), whose sum is σ = 13922080. Its totient is φ = 10441548.

The previous prime is 12181781. The next prime is 12181817. The reversal of 12181813 is 31818121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 31818121 = 31 ⋅1026391.

It is a cyclic number.

It is not a de Polignac number, because 12181813 - 2⁵ = 12181781 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12181817) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 870123 + ... + 870136.

It is an arithmetic number, because the mean of its divisors is an integer number (3480520).

Almost surely, 2^12181813 is an apocalyptic number.

It is an amenable number.

12181813 is a deficient number, since it is larger than the sum of its proper divisors (1740267).

12181813 is an equidigital number, since it uses as much as digits as its factorization.

12181813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1740266.

The product of its digits is 384, while the sum is 25.

The square root of 12181813 is about 3490.2454068446. The cubic root of 12181813 is about 230.0933017806.

Adding to 12181813 its reverse (31818121), we get a palindrome (43999934).

The spelling of 12181813 in words is "twelve million, one hundred eighty-one thousand, eight hundred thirteen".