281605 has 8 divisors (see below), whose sum is σ = 357912. Its totient is φ = 211968.

The previous prime is 281581. The next prime is 281609. The reversal of 281605 is 506182.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 123201 + 158404 = 351^2 + 398^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 281605 - 2¹¹ = 279557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (281609) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1572 + ... + 1741.

It is an arithmetic number, because the mean of its divisors is an integer number (44739).

2²⁸¹⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

281605 is a deficient number, since it is larger than the sum of its proper divisors (76307).

281605 is a wasteful number, since it uses less digits than its factorization.

281605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3335.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 281605 is about 530.6646775507. The cubic root of 281605 is about 65.5460895820.

Adding to 281605 its reverse (506182), we get a palindrome (787787).

The spelling of 281605 in words is "two hundred eighty-one thousand, six hundred five".