521561 has 4 divisors (see below), whose sum is σ = 534324. Its totient is φ = 508800.

The previous prime is 521557. The next prime is 521567. The reversal of 521561 is 165125.

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 225625 + 295936 = 475^2 + 544^2 .

It is a cyclic number.

It is not a de Polignac number, because 521561 - 2² = 521557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6320 + ... + 6401.

It is an arithmetic number, because the mean of its divisors is an integer number (133581).

2⁵²¹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

521561 is a deficient number, since it is larger than the sum of its proper divisors (12763).

521561 is a wasteful number, since it uses less digits than its factorization.

521561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12762.

The product of its digits is 300, while the sum is 20.

The square root of 521561 is about 722.1918027782. The cubic root of 521561 is about 80.4949008511.

Adding to 521561 its reverse (165125), we get a palindrome (686686).

The spelling of 521561 in words is "five hundred twenty-one thousand, five hundred sixty-one".