261687 has 8 divisors (see below), whose sum is σ = 367360. Its totient is φ = 165240.

The previous prime is 261673. The next prime is 261697. The reversal of 261687 is 786162.

It is a happy number.

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

It is not a de Polignac number, because 261687 - 2⁸ = 261431 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 261687.

It is not an unprimeable number, because it can be changed into a prime (261637) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2239 + ... + 2352.

It is an arithmetic number, because the mean of its divisors is an integer number (45920).

2²⁶¹⁶⁸⁷ is an apocalyptic number.

261687 is a deficient number, since it is larger than the sum of its proper divisors (105673).

261687 is a wasteful number, since it uses less digits than its factorization.

261687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4613.

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

The square root of 261687 is about 511.5535162620. The cubic root of 261687 is about 63.9627876121.

The spelling of 261687 in words is "two hundred sixty-one thousand, six hundred eighty-seven".