261861047811 has 96 divisors (see below), whose sum is σ = 425705492160. Its totient is φ = 155042933760.

The previous prime is 261861047801. The next prime is 261861047813. The reversal of 261861047811 is 118740168162.

261861047811 is a `hidden beast` number, since 2 + 6 + 18 + 610 + 4 + 7 + 8 + 11 = 666.

261861047811 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 261861047811 - 2⁹ = 261861047299 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261861047813) 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 in 95 ways as a sum of consecutive naturals, for example, 175862955 + ... + 175864443.

It is an arithmetic number, because the mean of its divisors is an integer number (4434432210).

Almost surely, 2^261861047811 is an apocalyptic number.

261861047811 is a deficient number, since it is larger than the sum of its proper divisors (163844444349).

261861047811 is a wasteful number, since it uses less digits than its factorization.

261861047811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1858 (or 1833 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The spelling of 261861047811 in words is "two hundred sixty-one billion, eight hundred sixty-one million, forty-seven thousand, eight hundred eleven".