261535122765569 has 2 divisors, whose sum is σ = 261535122765570. Its totient is φ = 261535122765568.

The previous prime is 261535122765533. The next prime is 261535122765583. The reversal of 261535122765569 is 965567221535162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 255434296865344 + 6100825900225 = 15982312^2 + 2469985^2 .

It is a cyclic number.

It is not a de Polignac number, because 261535122765569 - 2⁸ = 261535122765313 is a prime.

It is a super-2 number, since 2×261535122765569² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261535122765589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130767561382784 + 130767561382785.

It is an arithmetic number, because the mean of its divisors is an integer number (130767561382785).

Almost surely, 2^{261535122765569} is an apocalyptic number.

It is an amenable number.

261535122765569 is a deficient number, since it is larger than the sum of its proper divisors (1).

261535122765569 is an equidigital number, since it uses as much as digits as its factorization.

261535122765569 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 204120000, while the sum is 65.

The spelling of 261535122765569 in words is "two hundred sixty-one trillion, five hundred thirty-five billion, one hundred twenty-two million, seven hundred sixty-five thousand, five hundred sixty-nine".