213918181 has 4 divisors (see below), whose sum is σ = 221294700. Its totient is φ = 206541664.

The previous prime is 213918179. The next prime is 213918209. The reversal of 213918181 is 181819312.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 114597025 + 99321156 = 10705^2 + 9966^2 .

It is a cyclic number.

It is not a de Polignac number, because 213918181 - 2¹ = 213918179 is a prime.

It is a super-2 number, since 2×213918181² = 91521976324697522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213918161) 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 3 ways as a sum of consecutive naturals, for example, 3688216 + ... + 3688273.

It is an arithmetic number, because the mean of its divisors is an integer number (55323675).

Almost surely, 2^213918181 is an apocalyptic number.

It is an amenable number.

213918181 is a deficient number, since it is larger than the sum of its proper divisors (7376519).

213918181 is an equidigital number, since it uses as much as digits as its factorization.

213918181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7376518.

The product of its digits is 3456, while the sum is 34.

The square root of 213918181 is about 14625.9420551293. The cubic root of 213918181 is about 598.0661636393.

The spelling of 213918181 in words is "two hundred thirteen million, nine hundred eighteen thousand, one hundred eighty-one".