665220 has 24 divisors (see below), whose sum is σ = 1862784. Its totient is φ = 177376.

The previous prime is 665213. The next prime is 665221. The reversal of 665220 is 22566.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (665221) by changing a digit.

665220 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5484 + ... + 5603.

It is an arithmetic number, because the mean of its divisors is an integer number (77616).

2⁶⁶⁵²²⁰ is an apocalyptic number.

665220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

665220 is an abundant number, since it is smaller than the sum of its proper divisors (1197564).

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

665220 is a wasteful number, since it uses less digits than its factorization.

665220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11099 (or 11097 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 665220 is about 815.6102010152. The cubic root of 665220 is about 87.2948117248.

Adding to 665220 its reverse (22566), we get a palindrome (687786).

The spelling of 665220 in words is "six hundred sixty-five thousand, two hundred twenty".