261678 has 8 divisors (see below), whose sum is σ = 523368. Its totient is φ = 87224.

The previous prime is 261673. The next prime is 261697. The reversal of 261678 is 876162.

It is a happy number.

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

261678 is an admirable 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 (261673) by changing a digit.

261678 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, 21801 + ... + 21812.

It is an arithmetic number, because the mean of its divisors is an integer number (65421).

2²⁶¹⁶⁷⁸ is an apocalyptic number.

261678 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

261678 is a wasteful number, since it uses less digits than its factorization.

261678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43618.

The product of its digits is 4032, while the sum is 30.

The square root of 261678 is about 511.5447194528. The cubic root of 261678 is about 63.9620543293.

It can be divided in two parts, 261 and 678, that added together give a palindrome (939).

The spelling of 261678 in words is "two hundred sixty-one thousand, six hundred seventy-eight".