261536 has 24 divisors (see below), whose sum is σ = 562464. Its totient is φ = 118720.

The previous prime is 261529. The next prime is 261557. The reversal of 261536 is 635162.

It is a nialpdrome in base 8.

It is a congruent number.

It is an unprimeable number.

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, 20 + ... + 723.

It is an arithmetic number, because the mean of its divisors is an integer number (23436).

2²⁶¹⁵³⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (281232).

261536 is an abundant number, since it is smaller than the sum of its proper divisors (300928).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261536 is a wasteful number, since it uses less digits than its factorization.

261536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 764 (or 756 counting only the distinct ones).

The product of its digits is 1080, while the sum is 23.

The square root of 261536 is about 511.4059053237. The cubic root of 261536 is about 63.9504825310.

Adding to 261536 its reverse (635162), we get a palindrome (896698).

It can be divided in two parts, 261 and 536, that added together give a palindrome (797).

The spelling of 261536 in words is "two hundred sixty-one thousand, five hundred thirty-six".