261636240261 has 32 divisors (see below), whose sum is σ = 406343089152. Its totient is φ = 148145880960.

The previous prime is 261636240199. The next prime is 261636240277. The reversal of 261636240261 is 162042636162.

It is not a de Polignac number, because 261636240261 - 2⁷ = 261636240133 is a prime.

It is a super-3 number, since 3×261636240261³ (a number of 35 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261636240461) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3975640 + ... + 4040913.

It is an arithmetic number, because the mean of its divisors is an integer number (12698221536).

Almost surely, 2^261636240261 is an apocalyptic number.

It is an amenable number.

261636240261 is a deficient number, since it is larger than the sum of its proper divisors (144706848891).

261636240261 is a wasteful number, since it uses less digits than its factorization.

261636240261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8016633.

The product of its (nonzero) digits is 124416, while the sum is 39.

The spelling of 261636240261 in words is "two hundred sixty-one billion, six hundred thirty-six million, two hundred forty thousand, two hundred sixty-one".