281861 has 4 divisors (see below), whose sum is σ = 282924. Its totient is φ = 280800.

The previous prime is 281857. The next prime is 281867. The reversal of 281861 is 168182.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 96100 + 185761 = 310^2 + 431^2 .

It is a cyclic number.

It is not a de Polignac number, because 281861 - 2² = 281857 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 281861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (281867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 251 + ... + 791.

It is an arithmetic number, because the mean of its divisors is an integer number (70731).

2²⁸¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

281861 is a deficient number, since it is larger than the sum of its proper divisors (1063).

281861 is an equidigital number, since it uses as much as digits as its factorization.

281861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1062.

The product of its digits is 768, while the sum is 26.

The square root of 281861 is about 530.9058296911. The cubic root of 281861 is about 65.5659456650.

The spelling of 281861 in words is "two hundred eighty-one thousand, eight hundred sixty-one".