261241605 has 20 divisors (see below), whose sum is σ = 468300492. Its totient is φ = 139328640.

The previous prime is 261241573. The next prime is 261241609. The reversal of 261241605 is 506142162.

261241605 is a `hidden beast` number, since 2 + 6 + 12 + 41 + 605 = 666.

261241605 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 189365121 + 71876484 = 13761^2 + 8478^2 .

It is not a de Polignac number, because 261241605 - 2⁵ = 261241573 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261241609) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 322116 + ... + 322925.

Almost surely, 2^261241605 is an apocalyptic number.

It is an amenable number.

261241605 is a deficient number, since it is larger than the sum of its proper divisors (207058887).

261241605 is an equidigital number, since it uses as much as digits as its factorization.

261241605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 645058 (or 645049 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 261241605 is about 16162.9701787759. The cubic root of 261241605 is about 639.2647847965.

Adding to 261241605 its reverse (506142162), we get a palindrome (767383767).

The spelling of 261241605 in words is "two hundred sixty-one million, two hundred forty-one thousand, six hundred five".