521409 has 12 divisors (see below), whose sum is σ = 808944. Its totient is φ = 297864.

The previous prime is 521401. The next prime is 521429. The reversal of 521409 is 904125.

It is not a de Polignac number, because 521409 - 2³ = 521401 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

521409 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (521401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1627 + ... + 1920.

It is an arithmetic number, because the mean of its divisors is an integer number (67412).

2⁵²¹⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

521409 is a deficient number, since it is larger than the sum of its proper divisors (287535).

521409 is a wasteful number, since it uses less digits than its factorization.

521409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3564 (or 3557 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 521409 is about 722.0865599082. The cubic root of 521409 is about 80.4870804723.

The spelling of 521409 in words is "five hundred twenty-one thousand, four hundred nine".