261762771065666 has 16 divisors (see below), whose sum is σ = 422847844091064. Its totient is φ = 120813503551104.

The previous prime is 261762771065647. The next prime is 261762771065669. The reversal of 261762771065666 is 666560177267162.

It can be written as a sum of positive squares in 4 ways, for example, as 132398966925625 + 129363804140041 = 11506475^2 + 11373821^2 .

It is a junction number, because it is equal to n+sod(n) for n = 261762771065596 and 261762771065605.

It is not an unprimeable number, because it can be changed into a prime (261762771065669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51572846 + ... + 56420598.

Almost surely, 2^{261762771065666} is an apocalyptic number.

261762771065666 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

261762771065666 is a deficient number, since it is larger than the sum of its proper divisors (161085073025398).

261762771065666 is a wasteful number, since it uses less digits than its factorization.

261762771065666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6924565.

The product of its (nonzero) digits is 320060160, while the sum is 68.

The spelling of 261762771065666 in words is "two hundred sixty-one trillion, seven hundred sixty-two billion, seven hundred seventy-one million, sixty-five thousand, six hundred sixty-six".