261816 has 16 divisors (see below), whose sum is σ = 654600. Its totient is φ = 87264.

The previous prime is 261799. The next prime is 261823. The reversal of 261816 is 618162.

261816 is nontrivially palindromic in base 13.

261816 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 10909 = 261816 / (2 + 6 + 1 + 8 + 1 + 6).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

261816 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 3 ways as a sum of consecutive naturals, for example, 5431 + ... + 5478.

2²⁶¹⁸¹⁶ is an apocalyptic number.

It is an amenable number.

261816 is an abundant number, since it is smaller than the sum of its proper divisors (392784).

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

261816 is a wasteful number, since it uses less digits than its factorization.

261816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10918 (or 10914 counting only the distinct ones).

The product of its digits is 576, while the sum is 24.

The square root of 261816 is about 511.6795872419. The cubic root of 261816 is about 63.9732961511.

Adding to 261816 its reverse (618162), we get a palindrome (879978).

The spelling of 261816 in words is "two hundred sixty-one thousand, eight hundred sixteen".