521605 has 12 divisors (see below), whose sum is σ = 728460. Its totient is φ = 357504.

The previous prime is 521603. The next prime is 521641. The reversal of 521605 is 506125.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 159201 + 362404 = 399^2 + 602^2 .

It is not a de Polignac number, because 521605 - 2¹ = 521603 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521603) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 820 + ... + 1309.

It is an arithmetic number, because the mean of its divisors is an integer number (60705).

2⁵²¹⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

521605 is a deficient number, since it is larger than the sum of its proper divisors (206855).

521605 is a wasteful number, since it uses less digits than its factorization.

521605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2148 (or 2141 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 521605 is about 722.2222649573. Note that the first 4 decimals coincide. The cubic root of 521605 is about 80.4971643614.

The spelling of 521605 in words is "five hundred twenty-one thousand, six hundred five".