521840 has 40 divisors (see below), whose sum is σ = 1325808. Its totient is φ = 189440.

The previous prime is 521831. The next prime is 521861. The reversal of 521840 is 48125.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 584 + ... + 1176.

2⁵²¹⁸⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 521840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (662904).

521840 is an abundant number, since it is smaller than the sum of its proper divisors (803968).

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

521840 is a wasteful number, since it uses less digits than its factorization.

521840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 617 (or 611 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 521840 is about 722.3849389349. The cubic root of 521840 is about 80.5092514090.

Adding to 521840 its reverse (48125), we get a palindrome (569965).

The spelling of 521840 in words is "five hundred twenty-one thousand, eight hundred forty".