205521 has 4 divisors (see below), whose sum is σ = 274032. Its totient is φ = 137012.

The previous prime is 205519. The next prime is 205529. The reversal of 205521 is 125502.

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 205521 - 2¹ = 205519 is a prime.

It is a D-number.

205521 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 205521.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 205521.

It is not an unprimeable number, because it can be changed into a prime (205529) 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, 34251 + ... + 34256.

It is an arithmetic number, because the mean of its divisors is an integer number (68508).

2²⁰⁵⁵²¹ is an apocalyptic number.

It is an amenable number.

205521 is a deficient number, since it is larger than the sum of its proper divisors (68511).

205521 is an equidigital number, since it uses as much as digits as its factorization.

205521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68510.

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 205521 is about 453.3442400649. The cubic root of 205521 is about 59.0135944926.

The spelling of 205521 in words is "two hundred five thousand, five hundred twenty-one".