8561278261 has 2 divisors, whose sum is σ = 8561278262. Its totient is φ = 8561278260.

The previous prime is 8561278223. The next prime is 8561278283. The reversal of 8561278261 is 1628721658.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8559765361 + 1512900 = 92519^2 + 1230^2 .

It is a cyclic number.

It is not a de Polignac number, because 8561278261 - 2²¹ = 8559181109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8561278211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4280639130 + 4280639131.

It is an arithmetic number, because the mean of its divisors is an integer number (4280639131).

Almost surely, 2^8561278261 is an apocalyptic number.

It is an amenable number.

8561278261 is a deficient number, since it is larger than the sum of its proper divisors (1).

8561278261 is an equidigital number, since it uses as much as digits as its factorization.

8561278261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 322560, while the sum is 46.

The square root of 8561278261 is about 92527.1757971678. The cubic root of 8561278261 is about 2045.7200622261.

The spelling of 8561278261 in words is "eight billion, five hundred sixty-one million, two hundred seventy-eight thousand, two hundred sixty-one".