243622721 has 2 divisors, whose sum is σ = 243622722. Its totient is φ = 243622720.

The previous prime is 243622651. The next prime is 243622723. The reversal of 243622721 is 127226342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 209236225 + 34386496 = 14465^2 + 5864^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-243622721 is a prime.

Together with 243622723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (243622723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121811360 + 121811361.

It is an arithmetic number, because the mean of its divisors is an integer number (121811361).

Almost surely, 2^243622721 is an apocalyptic number.

It is an amenable number.

243622721 is a deficient number, since it is larger than the sum of its proper divisors (1).

243622721 is an equidigital number, since it uses as much as digits as its factorization.

243622721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8064, while the sum is 29.

The square root of 243622721 is about 15608.4182734831. The cubic root of 243622721 is about 624.5577423803.

The spelling of 243622721 in words is "two hundred forty-three million, six hundred twenty-two thousand, seven hundred twenty-one".