261409 has 4 divisors (see below), whose sum is σ = 276804. Its totient is φ = 246016.

The previous prime is 261407. The next prime is 261427. The reversal of 261409 is 904162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 245025 + 16384 = 495^2 + 128^2 .

It is a cyclic number.

It is not a de Polignac number, because 261409 - 2¹ = 261407 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 8.

It is a self number, because there is not a number n which added to its sum of digits gives 261409.

It is not an unprimeable number, because it can be changed into a prime (261407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7672 + ... + 7705.

It is an arithmetic number, because the mean of its divisors is an integer number (69201).

2²⁶¹⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

261409 is a deficient number, since it is larger than the sum of its proper divisors (15395).

261409 is a wasteful number, since it uses less digits than its factorization.

261409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15394.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 261409 is about 511.2817227322. The cubic root of 261409 is about 63.9401295570.

The spelling of 261409 in words is "two hundred sixty-one thousand, four hundred nine".