281561 has 16 divisors (see below), whose sum is σ = 355200. Its totient is φ = 217728.

The previous prime is 281557. The next prime is 281563. The reversal of 281561 is 165182.

It is not a de Polignac number, because 281561 - 2² = 281557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (281563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3821 + ... + 3893.

It is an arithmetic number, because the mean of its divisors is an integer number (22200).

2²⁸¹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

281561 is a deficient number, since it is larger than the sum of its proper divisors (73639).

281561 is a wasteful number, since it uses less digits than its factorization.

281561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128.

The product of its digits is 480, while the sum is 23.

The square root of 281561 is about 530.6232184894. The cubic root of 281561 is about 65.5426756059.

It can be divided in two parts, 281 and 561, that multiplied together give a triangular number (157641 = T₅₆₁).

The spelling of 281561 in words is "two hundred eighty-one thousand, five hundred sixty-one".