261534542861 has 2 divisors, whose sum is σ = 261534542862. Its totient is φ = 261534542860.

The previous prime is 261534542837. The next prime is 261534542873. The reversal of 261534542861 is 168245435162.

261534542861 is digitally balanced in base 2, 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., 214536638761 + 46997904100 = 463181^2 + 216790^2 .

It is a cyclic number.

It is not a de Polignac number, because 261534542861 - 2¹⁰ = 261534541837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261534542891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130767271430 + 130767271431.

It is an arithmetic number, because the mean of its divisors is an integer number (130767271431).

Almost surely, 2^261534542861 is an apocalyptic number.

It is an amenable number.

261534542861 is a deficient number, since it is larger than the sum of its proper divisors (1).

261534542861 is an equidigital number, since it uses as much as digits as its factorization.

261534542861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1382400, while the sum is 47.

The spelling of 261534542861 in words is "two hundred sixty-one billion, five hundred thirty-four million, five hundred forty-two thousand, eight hundred sixty-one".