666220 has 12 divisors (see below), whose sum is σ = 1399104. Its totient is φ = 266480.

The previous prime is 666203. The next prime is 666229. The reversal of 666220 is 22666.

It is a nialpdrome in base 7 and base 10.

It is a junction number, because it is equal to n+sod(n) for n = 666191 and 666200.

It is not an unprimeable number, because it can be changed into a prime (666229) by changing a digit.

666220 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, 16636 + ... + 16675.

It is an arithmetic number, because the mean of its divisors is an integer number (116592).

2⁶⁶⁶²²⁰ is an apocalyptic number.

It is an amenable number.

666220 is an abundant number, since it is smaller than the sum of its proper divisors (732884).

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

666220 is a wasteful number, since it uses less digits than its factorization.

666220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33320 (or 33318 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 666220 is about 816.2230087421. The cubic root of 666220 is about 87.3385321511.

Adding to 666220 its reverse (22666), we get a palindrome (688886).

The spelling of 666220 in words is "six hundred sixty-six thousand, two hundred twenty".