181181821 has 8 divisors (see below), whose sum is σ = 187612920. Its totient is φ = 174763008.

The previous prime is 181181809. The next prime is 181181843. The reversal of 181181821 is 128181181.

It can be written as a sum of positive squares in 4 ways, for example, as 46389721 + 134792100 = 6811^2 + 11610^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 181181821 - 2¹⁵ = 181149053 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 (181181521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35205 + ... + 40021.

It is an arithmetic number, because the mean of its divisors is an integer number (23451615).

Almost surely, 2^181181821 is an apocalyptic number.

It is an amenable number.

181181821 is a deficient number, since it is larger than the sum of its proper divisors (6431099).

181181821 is a wasteful number, since it uses less digits than its factorization.

181181821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6143.

The product of its digits is 1024, while the sum is 31.

The square root of 181181821 is about 13460.3796751800. The cubic root of 181181821 is about 565.8546295579.

The spelling of 181181821 in words is "one hundred eighty-one million, one hundred eighty-one thousand, eight hundred twenty-one".