243171221 has 2 divisors, whose sum is σ = 243171222. Its totient is φ = 243171220.

The previous prime is 243171217. The next prime is 243171233. The reversal of 243171221 is 122171342.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 126315121 + 116856100 = 11239^2 + 10810^2 .

It is a cyclic number.

It is not a de Polignac number, because 243171221 - 2² = 243171217 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243171241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121585610 + 121585611.

It is an arithmetic number, because the mean of its divisors is an integer number (121585611).

Almost surely, 2^243171221 is an apocalyptic number.

It is an amenable number.

243171221 is a deficient number, since it is larger than the sum of its proper divisors (1).

243171221 is an equidigital number, since it uses as much as digits as its factorization.

243171221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 672, while the sum is 23.

The square root of 243171221 is about 15593.9482171771. The cubic root of 243171221 is about 624.1716779504.

The spelling of 243171221 in words is "two hundred forty-three million, one hundred seventy-one thousand, two hundred twenty-one".