261853946181 has 16 divisors (see below), whose sum is σ = 387941736000. Its totient is φ = 174564813744.

The previous prime is 261853946173. The next prime is 261853946191. The reversal of 261853946181 is 181649358162.

It is a happy number.

261853946181 is a `hidden beast` number, since 2 + 6 + 18 + 5 + 3 + 9 + 4 + 618 + 1 = 666.

It is not a de Polignac number, because 261853946181 - 2³ = 261853946173 is a prime.

It is a super-2 number, since 2×261853946181² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261853946161) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1203675 + ... + 1404471.

It is an arithmetic number, because the mean of its divisors is an integer number (24246358500).

Almost surely, 2^261853946181 is an apocalyptic number.

It is an amenable number.

261853946181 is a deficient number, since it is larger than the sum of its proper divisors (126087789819).

261853946181 is a wasteful number, since it uses less digits than its factorization.

261853946181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249105 (or 249099 counting only the distinct ones).

The product of its digits is 2488320, while the sum is 54.

The spelling of 261853946181 in words is "two hundred sixty-one billion, eight hundred fifty-three million, nine hundred forty-six thousand, one hundred eighty-one".