243858721 has 2 divisors, whose sum is σ = 243858722. Its totient is φ = 243858720.

The previous prime is 243858697. The next prime is 243858733. The reversal of 243858721 is 127858342.

It is a happy number.

243858721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 185504400 + 58354321 = 13620^2 + 7639^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-243858721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (243858221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121929360 + 121929361.

It is an arithmetic number, because the mean of its divisors is an integer number (121929361).

Almost surely, 2^243858721 is an apocalyptic number.

It is an amenable number.

243858721 is a deficient number, since it is larger than the sum of its proper divisors (1).

243858721 is an equidigital number, since it uses as much as digits as its factorization.

243858721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 107520, while the sum is 40.

The square root of 243858721 is about 15615.9764664269. The cubic root of 243858721 is about 624.7593492715.

The spelling of 243858721 in words is "two hundred forty-three million, eight hundred fifty-eight thousand, seven hundred twenty-one".