520409 has 2 divisors, whose sum is σ = 520410. Its totient is φ = 520408.

The previous prime is 520393. The next prime is 520411. The reversal of 520409 is 904025.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 394384 + 126025 = 628^2 + 355^2 .

It is a cyclic number.

It is not a de Polignac number, because 520409 - 2⁴ = 520393 is a prime.

It is a super-3 number, since 3×520409³ = 422820125480333787, which contains 333 as substring.

Together with 520411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (520309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260204 + 260205.

It is an arithmetic number, because the mean of its divisors is an integer number (260205).

2⁵²⁰⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

520409 is a deficient number, since it is larger than the sum of its proper divisors (1).

520409 is an equidigital number, since it uses as much as digits as its factorization.

520409 is an evil number, because the sum of its binary digits is even.

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

The square root of 520409 is about 721.3937898263. The cubic root of 520409 is about 80.4355926830.

It can be divided in two parts, 520 and 409, that added together give a palindrome (929).

The spelling of 520409 in words is "five hundred twenty thousand, four hundred nine".