520991 has 4 divisors (see below), whose sum is σ = 527352. Its totient is φ = 514632.

The previous prime is 520981. The next prime is 521009. The reversal of 520991 is 199025.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 520991 - 2¹⁴ = 504607 is a prime.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a self number, because there is not a number n which added to its sum of digits gives 520991.

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 520991.

It is not an unprimeable number, because it can be changed into a prime (520921) 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, 3056 + ... + 3221.

It is an arithmetic number, because the mean of its divisors is an integer number (131838).

2⁵²⁰⁹⁹¹ is an apocalyptic number.

520991 is a deficient number, since it is larger than the sum of its proper divisors (6361).

520991 is an equidigital number, since it uses as much as digits as its factorization.

520991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6360.

The product of its (nonzero) digits is 810, while the sum is 26.

The square root of 520991 is about 721.7970628923. The cubic root of 520991 is about 80.4655665910.

The spelling of 520991 in words is "five hundred twenty thousand, nine hundred ninety-one".