261803 has 4 divisors (see below), whose sum is σ = 264600. Its totient is φ = 259008.

The previous prime is 261799. The next prime is 261823. The reversal of 261803 is 308162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 308162 = 2 ⋅154081.

It is a cyclic number.

It is not a de Polignac number, because 261803 - 2² = 261799 is a prime.

It is a Duffinian 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, 1253 + ... + 1446.

It is an arithmetic number, because the mean of its divisors is an integer number (66150).

2²⁶¹⁸⁰³ is an apocalyptic number.

261803 is a deficient number, since it is larger than the sum of its proper divisors (2797).

261803 is an equidigital number, since it uses as much as digits as its factorization.

261803 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2796.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 261803 is about 511.6668838219. Note that the first 3 decimals coincide. The cubic root of 261803 is about 63.9722373075.

Adding to 261803 its reverse (308162), we get a palindrome (569965).

The spelling of 261803 in words is "two hundred sixty-one thousand, eight hundred three".