261265505 has 8 divisors (see below), whose sum is σ = 313605672. Its totient is φ = 208954368.

The previous prime is 261265493. The next prime is 261265517. The reversal of 261265505 is 505562162.

It is an interprime number because it is at equal distance from previous prime (261265493) and next prime (261265517).

It can be written as a sum of positive squares in 4 ways, for example, as 25090081 + 236175424 = 5009^2 + 15368^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 261265505 - 2¹⁰ = 261264481 is a prime.

It is a Duffinian number.

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 7 ways as a sum of consecutive naturals, for example, 29249 + ... + 37121.

It is an arithmetic number, because the mean of its divisors is an integer number (39200709).

Almost surely, 2^261265505 is an apocalyptic number.

It is an amenable number.

261265505 is a deficient number, since it is larger than the sum of its proper divisors (52340167).

261265505 is an equidigital number, since it uses as much as digits as its factorization.

261265505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14515.

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

The square root of 261265505 is about 16163.7095061746. The cubic root of 261265505 is about 639.2842788359.

The spelling of 261265505 in words is "two hundred sixty-one million, two hundred sixty-five thousand, five hundred five".