261809255 has 16 divisors (see below), whose sum is σ = 324756000. Its totient is φ = 202508160.

The previous prime is 261809237. The next prime is 261809279. The reversal of 261809255 is 552908162.

It is not a de Polignac number, because 261809255 - 2²⁰ = 260760679 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10721 + ... + 25269.

It is an arithmetic number, because the mean of its divisors is an integer number (20297250).

Almost surely, 2^261809255 is an apocalyptic number.

261809255 is a deficient number, since it is larger than the sum of its proper divisors (62946745).

261809255 is a wasteful number, since it uses less digits than its factorization.

261809255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14674.

The product of its (nonzero) digits is 43200, while the sum is 38.

The square root of 261809255 is about 16180.5208507019. The cubic root of 261809255 is about 639.7274677853.

The spelling of 261809255 in words is "two hundred sixty-one million, eight hundred nine thousand, two hundred fifty-five".