521604 has 18 divisors (see below), whose sum is σ = 1318590. Its totient is φ = 173856.

The previous prime is 521603. The next prime is 521641. The reversal of 521604 is 406125.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 360000 + 161604 = 600^2 + 402^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (521603) 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 5 ways as a sum of consecutive naturals, for example, 7209 + ... + 7280.

It is an arithmetic number, because the mean of its divisors is an integer number (73255).

2⁵²¹⁶⁰⁴ is an apocalyptic number.

It is an amenable number.

521604 is an abundant number, since it is smaller than the sum of its proper divisors (796986).

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

521604 is a wasteful number, since it uses less digits than its factorization.

521604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14499 (or 14494 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 521604 is about 722.2215726493. The cubic root of 521604 is about 80.4971129194.

Adding to 521604 its reverse (406125), we get a palindrome (927729).

It can be divided in two parts, 5 and 21604, that added together give a square (21609 = 147²).

The spelling of 521604 in words is "five hundred twenty-one thousand, six hundred four".