521921 has 4 divisors (see below), whose sum is σ = 529344. Its totient is φ = 514500.

The previous prime is 521903. The next prime is 521923. The reversal of 521921 is 129125.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 521921 - 2¹⁴ = 505537 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 521893 and 521902.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 521921.

It is not an unprimeable number, because it can be changed into a prime (521923) 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, 3605 + ... + 3746.

It is an arithmetic number, because the mean of its divisors is an integer number (132336).

2⁵²¹⁹²¹ is an apocalyptic number.

It is an amenable number.

521921 is a deficient number, since it is larger than the sum of its proper divisors (7423).

521921 is an equidigital number, since it uses as much as digits as its factorization.

521921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7422.

The product of its digits is 180, while the sum is 20.

The square root of 521921 is about 722.4410010513. The cubic root of 521921 is about 80.5134167419.

The spelling of 521921 in words is "five hundred twenty-one thousand, nine hundred twenty-one".