281661 has 4 divisors (see below), whose sum is σ = 375552. Its totient is φ = 187772.

The previous prime is 281653. The next prime is 281663. The reversal of 281661 is 166182.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 281661 - 2³ = 281653 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (281663) 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, 46941 + ... + 46946.

It is an arithmetic number, because the mean of its divisors is an integer number (93888).

2²⁸¹⁶⁶¹ is an apocalyptic number.

It is an amenable number.

281661 is a deficient number, since it is larger than the sum of its proper divisors (93891).

281661 is an equidigital number, since it uses as much as digits as its factorization.

281661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93890.

The product of its digits is 576, while the sum is 24.

The square root of 281661 is about 530.7174389447. The cubic root of 281661 is about 65.5504341281.

The spelling of 281661 in words is "two hundred eighty-one thousand, six hundred sixty-one".