2181181813 has 2 divisors, whose sum is σ = 2181181814. Its totient is φ = 2181181812.

The previous prime is 2181181799. The next prime is 2181181859. The reversal of 2181181813 is 3181811812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1949928964 + 231252849 = 44158^2 + 15207^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2181181813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2181181913) 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 as a sum of consecutive naturals, namely, 1090590906 + 1090590907.

It is an arithmetic number, because the mean of its divisors is an integer number (1090590907).

Almost surely, 2^2181181813 is an apocalyptic number.

It is an amenable number.

2181181813 is a deficient number, since it is larger than the sum of its proper divisors (1).

2181181813 is an equidigital number, since it uses as much as digits as its factorization.

2181181813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3072, while the sum is 34.

The square root of 2181181813 is about 46703.1242316828. The cubic root of 2181181813 is about 1296.8725241182.

The spelling of 2181181813 in words is "two billion, one hundred eighty-one million, one hundred eighty-one thousand, eight hundred thirteen".