1016720561 has 2 divisors, whose sum is σ = 1016720562. Its totient is φ = 1016720560.

The previous prime is 1016720557. The next prime is 1016720563. The reversal of 1016720561 is 1650276101.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 768342961 + 248377600 = 27719^2 + 15760^2 .

It is a cyclic number.

It is not a de Polignac number, because 1016720561 - 2² = 1016720557 is a prime.

Together with 1016720563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1016720563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 508360280 + 508360281.

It is an arithmetic number, because the mean of its divisors is an integer number (508360281).

Almost surely, 2^1016720561 is an apocalyptic number.

It is an amenable number.

1016720561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1016720561 is an equidigital number, since it uses as much as digits as its factorization.

1016720561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 1016720561 is about 31886.0559022279. The cubic root of 1016720561 is about 1005.5427415877.

Adding to 1016720561 its reverse (1650276101), we get a palindrome (2666996662).

The spelling of 1016720561 in words is "one billion, sixteen million, seven hundred twenty thousand, five hundred sixty-one".