281521 has 4 divisors (see below), whose sum is σ = 288112. Its totient is φ = 274932.

The previous prime is 281509. The next prime is 281527. The reversal of 281521 is 125182.

281521 is nontrivially palindromic in base 7.

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, and also an emirpimes, since its reverse is a distinct semiprime: 125182 = 2 ⋅62591.

It is a cyclic number.

It is not a de Polignac number, because 281521 - 2¹⁵ = 248753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (281527) 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, 3231 + ... + 3316.

It is an arithmetic number, because the mean of its divisors is an integer number (72028).

2²⁸¹⁵²¹ is an apocalyptic number.

It is an amenable number.

281521 is a deficient number, since it is larger than the sum of its proper divisors (6591).

281521 is an equidigital number, since it uses as much as digits as its factorization.

281521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6590.

The product of its digits is 160, while the sum is 19.

The square root of 281521 is about 530.5855256224. The cubic root of 281521 is about 65.5395716827.

The spelling of 281521 in words is "two hundred eighty-one thousand, five hundred twenty-one".