261801 has 12 divisors (see below), whose sum is σ = 398320. Its totient is φ = 165240.

The previous prime is 261799. The next prime is 261823. The reversal of 261801 is 108162.

It is not a de Polignac number, because 261801 - 2¹ = 261799 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 4.

It is not an unprimeable number, because it can be changed into a prime (261881) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 595 + ... + 936.

2²⁶¹⁸⁰¹ is an apocalyptic number.

It is an amenable number.

261801 is a deficient number, since it is larger than the sum of its proper divisors (136519).

261801 is a wasteful number, since it uses less digits than its factorization.

261801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1556 (or 1553 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 261801 is about 511.6649294216. The cubic root of 261801 is about 63.9720744053.

Adding to 261801 its reverse (108162), we get a palindrome (369963).

The spelling of 261801 in words is "two hundred sixty-one thousand, eight hundred one".