7785805561 has 2 divisors, whose sum is σ = 7785805562. Its totient is φ = 7785805560.

The previous prime is 7785805553. The next prime is 7785805591. The reversal of 7785805561 is 1655085877.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4851958336 + 2933847225 = 69656^2 + 54165^2 .

It is a cyclic number.

It is not a de Polignac number, because 7785805561 - 2³ = 7785805553 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 7785805499 and 7785805508.

It is not a weakly prime, because it can be changed into another prime (7785805591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3892902780 + 3892902781.

It is an arithmetic number, because the mean of its divisors is an integer number (3892902781).

Almost surely, 2^7785805561 is an apocalyptic number.

It is an amenable number.

7785805561 is a deficient number, since it is larger than the sum of its proper divisors (1).

7785805561 is an equidigital number, since it uses as much as digits as its factorization.

7785805561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2352000, while the sum is 52.

The square root of 7785805561 is about 88237.2118836492. The cubic root of 7785805561 is about 1981.9887477244.

The spelling of 7785805561 in words is "seven billion, seven hundred eighty-five million, eight hundred five thousand, five hundred sixty-one".