520021 has 2 divisors, whose sum is σ = 520022. Its totient is φ = 520020.

The previous prime is 520019. The next prime is 520031. The reversal of 520021 is 120025.

It is an a-pointer prime, because the next prime (520031) can be obtained adding 520021 to its sum of digits (10).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 280900 + 239121 = 530^2 + 489^2 .

It is a cyclic number.

It is not a de Polignac number, because 520021 - 2¹ = 520019 is a prime.

Together with 520019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (520031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260010 + 260011.

It is an arithmetic number, because the mean of its divisors is an integer number (260011).

2⁵²⁰⁰²¹ is an apocalyptic number.

It is an amenable number.

520021 is a deficient number, since it is larger than the sum of its proper divisors (1).

520021 is an equidigital number, since it uses as much as digits as its factorization.

520021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20, while the sum is 10.

The square root of 520021 is about 721.1248158259. The cubic root of 520021 is about 80.4155976603.

Adding to 520021 its reverse (120025), we get a palindrome (640046).

It can be divided in two parts, 52002 and 1, that added together give a triangular number (52003 = T₃₂₂).

The spelling of 520021 in words is "five hundred twenty thousand, twenty-one".