317720561 has 2 divisors, whose sum is σ = 317720562. Its totient is φ = 317720560.

The previous prime is 317720537. The next prime is 317720563. The reversal of 317720561 is 165027713.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 199346161 + 118374400 = 14119^2 + 10880^2 .

It is an emirp because it is prime and its reverse (165027713) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-317720561 is a prime.

It is a Sophie Germain prime.

Together with 317720563, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (317720563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 158860280 + 158860281.

It is an arithmetic number, because the mean of its divisors is an integer number (158860281).

Almost surely, 2^317720561 is an apocalyptic number.

It is an amenable number.

317720561 is a deficient number, since it is larger than the sum of its proper divisors (1).

317720561 is an equidigital number, since it uses as much as digits as its factorization.

317720561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8820, while the sum is 32.

The square root of 317720561 is about 17824.7176976243. The cubic root of 317720561 is about 682.3624296600.

The spelling of 317720561 in words is "three hundred seventeen million, seven hundred twenty thousand, five hundred sixty-one".