520661 has 4 divisors (see below), whose sum is σ = 522732. Its totient is φ = 518592.

The previous prime is 520649. The next prime is 520679. The reversal of 520661 is 166025.

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 398161 + 122500 = 631^2 + 350^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-520661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 520661.

It is not an unprimeable number, because it can be changed into a prime (520621) 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, 596 + ... + 1181.

It is an arithmetic number, because the mean of its divisors is an integer number (130683).

2⁵²⁰⁶⁶¹ is an apocalyptic number.

It is an amenable number.

520661 is a deficient number, since it is larger than the sum of its proper divisors (2071).

520661 is a wasteful number, since it uses less digits than its factorization.

520661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2070.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 520661 is about 721.5684305733. The cubic root of 520661 is about 80.4485738180.

Adding to 520661 its reverse (166025), we get a palindrome (686686).

The spelling of 520661 in words is "five hundred twenty thousand, six hundred sixty-one".