7811171561 has 2 divisors, whose sum is σ = 7811171562. Its totient is φ = 7811171560.

The previous prime is 7811171513. The next prime is 7811171569. The reversal of 7811171561 is 1651711187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6896472025 + 914699536 = 83045^2 + 30244^2 .

It is a cyclic number.

It is not a de Polignac number, because 7811171561 - 2⁶ = 7811171497 is a prime.

It is a super-2 number, since 2×7811171561² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (7811171569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3905585780 + 3905585781.

It is an arithmetic number, because the mean of its divisors is an integer number (3905585781).

Almost surely, 2^7811171561 is an apocalyptic number.

It is an amenable number.

7811171561 is a deficient number, since it is larger than the sum of its proper divisors (1).

7811171561 is an equidigital number, since it uses as much as digits as its factorization.

7811171561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11760, while the sum is 38.

The square root of 7811171561 is about 88380.8325430350. The cubic root of 7811171561 is about 1984.1388410935.

The spelling of 7811171561 in words is "seven billion, eight hundred eleven million, one hundred seventy-one thousand, five hundred sixty-one".