243722215661 has 2 divisors, whose sum is σ = 243722215662. Its totient is φ = 243722215660.

The previous prime is 243722215651. The next prime is 243722215717. The reversal of 243722215661 is 166512227342.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 172162755625 + 71559460036 = 414925^2 + 267506^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-243722215661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243722215601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121861107830 + 121861107831.

It is an arithmetic number, because the mean of its divisors is an integer number (121861107831).

Almost surely, 2^243722215661 is an apocalyptic number.

It is an amenable number.

243722215661 is a deficient number, since it is larger than the sum of its proper divisors (1).

243722215661 is an equidigital number, since it uses as much as digits as its factorization.

243722215661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 241920, while the sum is 41.

The spelling of 243722215661 in words is "two hundred forty-three billion, seven hundred twenty-two million, two hundred fifteen thousand, six hundred sixty-one".