813316561 has 2 divisors, whose sum is σ = 813316562. Its totient is φ = 813316560.

The previous prime is 813316519. The next prime is 813316583. The reversal of 813316561 is 165613318.

813316561 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., 451137600 + 362178961 = 21240^2 + 19031^2 .

It is a cyclic number.

It is not a de Polignac number, because 813316561 - 2¹⁷ = 813185489 is a prime.

It is a super-2 number, since 2×813316561² = 1322967656793733442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (813311561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 406658280 + 406658281.

It is an arithmetic number, because the mean of its divisors is an integer number (406658281).

Almost surely, 2^813316561 is an apocalyptic number.

It is an amenable number.

813316561 is a deficient number, since it is larger than the sum of its proper divisors (1).

813316561 is an equidigital number, since it uses as much as digits as its factorization.

813316561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 34.

The square root of 813316561 is about 28518.7054579972. The cubic root of 813316561 is about 933.4402817780.

Adding to 813316561 its reverse (165613318), we get a palindrome (978929879).

The spelling of 813316561 in words is "eight hundred thirteen million, three hundred sixteen thousand, five hundred sixty-one".