261543072657555 has 72 divisors (see below), whose sum is σ = 518621511884112. Its totient is φ = 121185568429056.

The previous prime is 261543072657541. The next prime is 261543072657563. The reversal of 261543072657555 is 555756270345162.

It is a happy number.

261543072657555 is a `hidden beast` number, since 2 + 6 + 1 + 5 + 4 + 3 + 0 + 7 + 2 + 6 + 575 + 55 = 666.

It is not a de Polignac number, because 261543072657555 - 2⁹ = 261543072657043 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 261543072657492 and 261543072657501.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 773329509 + ... + 773667638.

It is an arithmetic number, because the mean of its divisors is an integer number (7203076553946).

Almost surely, 2^{261543072657555} is an apocalyptic number.

261543072657555 is a deficient number, since it is larger than the sum of its proper divisors (257078439226557).

261543072657555 is a wasteful number, since it uses less digits than its factorization.

261543072657555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1546997205 (or 1546997185 counting only the distinct ones).

The product of its (nonzero) digits is 264600000, while the sum is 63.

The spelling of 261543072657555 in words is "two hundred sixty-one trillion, five hundred forty-three billion, seventy-two million, six hundred fifty-seven thousand, five hundred fifty-five".