243213181 has 2 divisors, whose sum is σ = 243213182. Its totient is φ = 243213180.

The previous prime is 243213143. The next prime is 243213199. The reversal of 243213181 is 181312342.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 229037956 + 14175225 = 15134^2 + 3765^2 .

It is a cyclic number.

It is not a de Polignac number, because 243213181 - 2²³ = 234824573 is a prime.

It is a super-2 number, since 2×243213181² = 118305302824277522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243213121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121606590 + 121606591.

It is an arithmetic number, because the mean of its divisors is an integer number (121606591).

Almost surely, 2^243213181 is an apocalyptic number.

It is an amenable number.

243213181 is a deficient number, since it is larger than the sum of its proper divisors (1).

243213181 is an equidigital number, since it uses as much as digits as its factorization.

243213181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 25.

The square root of 243213181 is about 15595.2935528640. The cubic root of 243213181 is about 624.2075768495.

The spelling of 243213181 in words is "two hundred forty-three million, two hundred thirteen thousand, one hundred eighty-one".