261655511230665 has 48 divisors (see below), whose sum is σ = 470336561368128. Its totient is φ = 139548803662656.

The previous prime is 261655511230601. The next prime is 261655511230667. The reversal of 261655511230665 is 566032115556162.

261655511230665 is a `hidden beast` number, since 2 + 6 + 1 + 6 + 5 + 551 + 1 + 23 + 0 + 6 + 65 = 666.

It is not a de Polignac number, because 261655511230665 - 2⁶ = 261655511230601 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261655511230667) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 253805734 + ... + 254834576.

It is an arithmetic number, because the mean of its divisors is an integer number (9798678361836).

Almost surely, 2^{261655511230665} is an apocalyptic number.

It is an amenable number.

261655511230665 is a deficient number, since it is larger than the sum of its proper divisors (208681050137463).

261655511230665 is a wasteful number, since it uses less digits than its factorization.

261655511230665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1238180 (or 1238168 counting only the distinct ones).

The product of its (nonzero) digits is 9720000, while the sum is 54.

The spelling of 261655511230665 in words is "two hundred sixty-one trillion, six hundred fifty-five billion, five hundred eleven million, two hundred thirty thousand, six hundred sixty-five".