261839 has 4 divisors (see below), whose sum is σ = 275640. Its totient is φ = 248040.

The previous prime is 261823. The next prime is 261847. The reversal of 261839 is 938162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261839 - 2⁴ = 261823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261439) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6872 + ... + 6909.

It is an arithmetic number, because the mean of its divisors is an integer number (68910).

2²⁶¹⁸³⁹ is an apocalyptic number.

261839 is a deficient number, since it is larger than the sum of its proper divisors (13801).

261839 is a wasteful number, since it uses less digits than its factorization.

261839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13800.

The product of its digits is 2592, while the sum is 29.

The square root of 261839 is about 511.7020617508. The cubic root of 261839 is about 63.9751694040.

The spelling of 261839 in words is "two hundred sixty-one thousand, eight hundred thirty-nine".