261025565 has 16 divisors (see below), whose sum is σ = 340623792. Its totient is φ = 191222784.

The previous prime is 261025543. The next prime is 261025571. The reversal of 261025565 is 565520162.

It can be written as a sum of positive squares in 8 ways, for example, as 36445369 + 224580196 = 6037^2 + 14986^2 .

It is a cyclic number.

It is not a de Polignac number, because 261025565 - 2²⁰ = 259976989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38354 + ... + 44643.

It is an arithmetic number, because the mean of its divisors is an integer number (21288987).

Almost surely, 2^261025565 is an apocalyptic number.

It is an amenable number.

261025565 is a deficient number, since it is larger than the sum of its proper divisors (79598227).

261025565 is a wasteful number, since it uses less digits than its factorization.

261025565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83056.

The product of its (nonzero) digits is 18000, while the sum is 32.

The square root of 261025565 is about 16156.2856189162. The cubic root of 261025565 is about 639.0885177584.

The spelling of 261025565 in words is "two hundred sixty-one million, twenty-five thousand, five hundred sixty-five".