261824 has 14 divisors (see below), whose sum is σ = 519684. Its totient is φ = 130880.

The previous prime is 261823. The next prime is 261847. The reversal of 261824 is 428162.

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 261824.

It is not an unprimeable number, because it can be changed into a prime (261823) 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 as a sum of consecutive naturals, namely, 1982 + ... + 2109.

2²⁶¹⁸²⁴ is an apocalyptic number.

It is an amenable number.

261824 is a deficient number, since it is larger than the sum of its proper divisors (257860).

261824 is an equidigital number, since it uses as much as digits as its factorization.

261824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4103 (or 4093 counting only the distinct ones).

The product of its digits is 768, while the sum is 23.

The square root of 261824 is about 511.6874045743. The cubic root of 261824 is about 63.9739477298.

Adding to 261824 its reverse (428162), we get a palindrome (689986).

The spelling of 261824 in words is "two hundred sixty-one thousand, eight hundred twenty-four".