521209 has 4 divisors (see below), whose sum is σ = 561316. Its totient is φ = 481104.

The previous prime is 521201. The next prime is 521231. The reversal of 521209 is 902125.

521209 is nontrivially palindromic in base 8.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 51984 + 469225 = 228^2 + 685^2 .

It is not a de Polignac number, because 521209 - 2³ = 521201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521201) 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, 20034 + ... + 20059.

It is an arithmetic number, because the mean of its divisors is an integer number (140329).

2⁵²¹²⁰⁹ is an apocalyptic number.

It is an amenable number.

521209 is a deficient number, since it is larger than the sum of its proper divisors (40107).

521209 is a wasteful number, since it uses less digits than its factorization.

521209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40106.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 521209 is about 721.9480590735. The cubic root of 521209 is about 80.4767881844.

The spelling of 521209 in words is "five hundred twenty-one thousand, two hundred nine".