664220 has 12 divisors (see below), whose sum is σ = 1394904. Its totient is φ = 265680.

The previous prime is 664211. The next prime is 664243. The reversal of 664220 is 22466.

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 33211 = 664220 / (6 + 6 + 4 + 2 + 2 + 0).

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 664192 and 664201.

It is a congruent number.

It is an unprimeable number.

664220 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16586 + ... + 16625.

It is an arithmetic number, because the mean of its divisors is an integer number (116242).

2⁶⁶⁴²²⁰ is an apocalyptic number.

It is an amenable number.

664220 is an abundant number, since it is smaller than the sum of its proper divisors (730684).

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

664220 is a wasteful number, since it uses less digits than its factorization.

664220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33220 (or 33218 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 664220 is about 814.9969325096. The cubic root of 664220 is about 87.2510474610.

Adding to 664220 its reverse (22466), we get a palindrome (686686).

The spelling of 664220 in words is "six hundred sixty-four thousand, two hundred twenty".