261863 has 4 divisors (see below), whose sum is σ = 299280. Its totient is φ = 224448.

The previous prime is 261847. The next prime is 261881. The reversal of 261863 is 368162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 368162 = 2 ⋅184081.

It is not a de Polignac number, because 261863 - 2⁴ = 261847 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 (261823) 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, 18698 + ... + 18711.

It is an arithmetic number, because the mean of its divisors is an integer number (74820).

2²⁶¹⁸⁶³ is an apocalyptic number.

261863 is a deficient number, since it is larger than the sum of its proper divisors (37417).

261863 is an equidigital number, since it uses as much as digits as its factorization.

261863 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37416.

The product of its digits is 1728, while the sum is 26.

The square root of 261863 is about 511.7255123599. The cubic root of 261863 is about 63.9771239857.

The spelling of 261863 in words is "two hundred sixty-one thousand, eight hundred sixty-three".