646221 has 8 divisors (see below), whose sum is σ = 912384. Its totient is φ = 405440.

The previous prime is 646199. The next prime is 646237. The reversal of 646221 is 122646.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 646221 - 2⁵ = 646189 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6285 + ... + 6386.

It is an arithmetic number, because the mean of its divisors is an integer number (114048).

2⁶⁴⁶²²¹ is an apocalyptic number.

It is an amenable number.

646221 is a deficient number, since it is larger than the sum of its proper divisors (266163).

646221 is a wasteful number, since it uses less digits than its factorization.

646221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12691.

The product of its digits is 576, while the sum is 21.

The square root of 646221 is about 803.8787221963. The cubic root of 646221 is about 86.4557114542.

Adding to 646221 its reverse (122646), we get a palindrome (768867).

The spelling of 646221 in words is "six hundred forty-six thousand, two hundred twenty-one".