521540 has 24 divisors (see below), whose sum is σ = 1111320. Its totient is φ = 205568.

The previous prime is 521539. The next prime is 521551. The reversal of 521540 is 45125.

It can be written as a sum of positive squares in 4 ways, for example, as 91204 + 430336 = 302^2 + 656^2 .

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1634 + ... + 1926.

It is an arithmetic number, because the mean of its divisors is an integer number (46305).

2⁵²¹⁵⁴⁰ is an apocalyptic number.

It is an amenable number.

521540 is an abundant number, since it is smaller than the sum of its proper divisors (589780).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

521540 is a wasteful number, since it uses less digits than its factorization.

521540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391 (or 389 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 521540 is about 722.1772635579. The cubic root of 521540 is about 80.4938204945.

Adding to 521540 its reverse (45125), we get a palindrome (566665).

The spelling of 521540 in words is "five hundred twenty-one thousand, five hundred forty".