261785 has 8 divisors (see below), whose sum is σ = 322056. Its totient is φ = 204160.

The previous prime is 261773. The next prime is 261787. The reversal of 261785 is 587162.

It can be written as a sum of positive squares in 4 ways, for example, as 3721 + 258064 = 61^2 + 508^2 .

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

It is not a de Polignac number, because 261785 - 2⁶ = 261721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261787) by changing a digit.

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, 434 + ... + 843.

It is an arithmetic number, because the mean of its divisors is an integer number (40257).

261785 is a Friedman number, since it can be written as 8^6-51*7-2, using all its digits and the basic arithmetic operations.

2²⁶¹⁷⁸⁵ is an apocalyptic number.

It is an amenable number.

261785 is a deficient number, since it is larger than the sum of its proper divisors (60271).

261785 is a wasteful number, since it uses less digits than its factorization.

261785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1323.

The product of its digits is 3360, while the sum is 29.

The square root of 261785 is about 511.6492939505. The cubic root of 261785 is about 63.9707711584.

The spelling of 261785 in words is "two hundred sixty-one thousand, seven hundred eighty-five".