776720561 has 2 divisors, whose sum is σ = 776720562. Its totient is φ = 776720560.

The previous prime is 776720521. The next prime is 776720569. The reversal of 776720561 is 165027677.

776720561 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., 710542336 + 66178225 = 26656^2 + 8135^2 .

It is a cyclic number.

It is not a de Polignac number, because 776720561 - 2²⁶ = 709611697 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (776720569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 388360280 + 388360281.

It is an arithmetic number, because the mean of its divisors is an integer number (388360281).

Almost surely, 2^776720561 is an apocalyptic number.

It is an amenable number.

776720561 is a deficient number, since it is larger than the sum of its proper divisors (1).

776720561 is an equidigital number, since it uses as much as digits as its factorization.

776720561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 123480, while the sum is 41.

The square root of 776720561 is about 27869.7068696461. The cubic root of 776720561 is about 919.2245201985.

The spelling of 776720561 in words is "seven hundred seventy-six million, seven hundred twenty thousand, five hundred sixty-one".