7817192561 has 2 divisors, whose sum is σ = 7817192562. Its totient is φ = 7817192560.

The previous prime is 7817192557. The next prime is 7817192563. The reversal of 7817192561 is 1652917187.

7817192561 is digitally balanced in base 3, 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., 6341096161 + 1476096400 = 79631^2 + 38420^2 .

It is a cyclic number.

It is not a de Polignac number, because 7817192561 - 2² = 7817192557 is a prime.

It is a super-2 number, since 2×7817192561² (a number of 21 digits) contains 22 as substring.

Together with 7817192563, 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 (7817192563) 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, 3908596280 + 3908596281.

It is an arithmetic number, because the mean of its divisors is an integer number (3908596281).

Almost surely, 2^7817192561 is an apocalyptic number.

It is an amenable number.

7817192561 is a deficient number, since it is larger than the sum of its proper divisors (1).

7817192561 is an equidigital number, since it uses as much as digits as its factorization.

7817192561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 211680, while the sum is 47.

The square root of 7817192561 is about 88414.8887970799. Note that the first 3 decimals coincide. The cubic root of 7817192561 is about 1984.6485141795.

The spelling of 7817192561 in words is "seven billion, eight hundred seventeen million, one hundred ninety-two thousand, five hundred sixty-one".