261205136 has 30 divisors (see below), whose sum is σ = 537615330. Its totient is φ = 122917888.

The previous prime is 261205127. The next prime is 261205151. The reversal of 261205136 is 631502162.

261205136 is digitally balanced in base 3, 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 3 ways, for example, as 77440000 + 183765136 = 8800^2 + 13556^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 23621 + ... + 32868.

It is an arithmetic number, because the mean of its divisors is an integer number (17920511).

Almost surely, 2^261205136 is an apocalyptic number.

It is an amenable number.

261205136 is an abundant number, since it is smaller than the sum of its proper divisors (276410194).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261205136 is a wasteful number, since it uses less digits than its factorization.

261205136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56531 (or 56508 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 261205136 is about 16161.8419742305. The cubic root of 261205136 is about 639.2350365585.

Adding to 261205136 its reverse (631502162), we get a palindrome (892707298).

The spelling of 261205136 in words is "two hundred sixty-one million, two hundred five thousand, one hundred thirty-six".