261440640234605 has 32 divisors (see below), whose sum is σ = 339280649326080. Its totient is φ = 192253083079680.

The previous prime is 261440640234577. The next prime is 261440640234649. The reversal of 261440640234605 is 506432046044162.

It is not a de Polignac number, because 261440640234605 - 2¹⁰ = 261440640233581 is a prime.

It is a super-3 number, since 3×261440640234605³ (a number of 44 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 261440640234605.

It is a congruent number.

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 31 ways as a sum of consecutive naturals, for example, 1843514150 + ... + 1843655960.

It is an arithmetic number, because the mean of its divisors is an integer number (10602520291440).

Almost surely, 2^{261440640234605} is an apocalyptic number.

It is an amenable number.

261440640234605 is a deficient number, since it is larger than the sum of its proper divisors (77840009091475).

261440640234605 is a wasteful number, since it uses less digits than its factorization.

261440640234605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260741.

The product of its (nonzero) digits is 3317760, while the sum is 47.

Adding to 261440640234605 its reverse (506432046044162), we get a palindrome (767872686278767).

The spelling of 261440640234605 in words is "two hundred sixty-one trillion, four hundred forty billion, six hundred forty million, two hundred thirty-four thousand, six hundred five".