7818755561 has 2 divisors, whose sum is σ = 7818755562. Its totient is φ = 7818755560.

The previous prime is 7818755557. The next prime is 7818755573. The reversal of 7818755561 is 1655578187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5586665536 + 2232090025 = 74744^2 + 47245^2 .

It is a cyclic number.

It is not a de Polignac number, because 7818755561 - 2² = 7818755557 is a prime.

It is a super-2 number, since 2×7818755561² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (7818755501) 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, 3909377780 + 3909377781.

It is an arithmetic number, because the mean of its divisors is an integer number (3909377781).

Almost surely, 2^7818755561 is an apocalyptic number.

It is an amenable number.

7818755561 is a deficient number, since it is larger than the sum of its proper divisors (1).

7818755561 is an equidigital number, since it uses as much as digits as its factorization.

7818755561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2352000, while the sum is 53.

The square root of 7818755561 is about 88423.7273643223. The cubic root of 7818755561 is about 1984.7807781555.

The spelling of 7818755561 in words is "seven billion, eight hundred eighteen million, seven hundred fifty-five thousand, five hundred sixty-one".