18261 has 6 divisors (see below), whose sum is σ = 26390. Its totient is φ = 12168.

The previous prime is 18257. The next prime is 18269. The reversal of 18261 is 16281.

It can be written as a sum of positive squares in only one way, i.e., 18225 + 36 = 135^2 + 6^2 .

It is not a de Polignac number, because 18261 - 2² = 18257 is a prime.

It is a Duffinian number.

It is a Curzon number.

18261 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18269) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1006 + ... + 1023.

2¹⁸²⁶¹ is an apocalyptic number.

It is an amenable number.

18261 is a deficient number, since it is larger than the sum of its proper divisors (8129).

18261 is a wasteful number, since it uses less digits than its factorization.

18261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2035 (or 2032 counting only the distinct ones).

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

The square root of 18261 is about 135.1332675547. The cubic root of 18261 is about 26.3334757599. Note that the first 3 decimals are identical.

It can be divided in two parts, 182 and 61, that added together give a 5-th power (243 = 3⁵).

The spelling of 18261 in words is "eighteen thousand, two hundred sixty-one".