664520 has 32 divisors (see below), whose sum is σ = 1539000. Its totient is φ = 258048.

The previous prime is 664511. The next prime is 664529. The reversal of 664520 is 25466.

It is an interprime number because it is at equal distance from previous prime (664511) and next prime (664529).

It can be written as a sum of positive squares in 4 ways, for example, as 643204 + 21316 = 802^2 + 146^2 .

It is not an unprimeable number, because it can be changed into a prime (664529) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1256 + ... + 1704.

2⁶⁶⁴⁵²⁰ 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 664520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (769500).

664520 is an abundant number, since it is smaller than the sum of its proper divisors (874480).

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

664520 is a wasteful number, since it uses less digits than its factorization.

664520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497 (or 493 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 664520 is about 815.1809615049. The cubic root of 664520 is about 87.2641813496.

Adding to 664520 its reverse (25466), we get a palindrome (689986).

The spelling of 664520 in words is "six hundred sixty-four thousand, five hundred twenty".