646755221 has 16 divisors (see below), whose sum is σ = 751862400. Its totient is φ = 544864320.

The previous prime is 646755209. The next prime is 646755281. The reversal of 646755221 is 122557646.

646755221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 646755221 - 2¹⁰ = 646754197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646755281) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 252455 + ... + 255003.

It is an arithmetic number, because the mean of its divisors is an integer number (46991400).

Almost surely, 2^646755221 is an apocalyptic number.

It is an amenable number.

646755221 is a deficient number, since it is larger than the sum of its proper divisors (105107179).

646755221 is a wasteful number, since it uses less digits than its factorization.

646755221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3164.

The product of its digits is 100800, while the sum is 38.

The square root of 646755221 is about 25431.3826010306. The cubic root of 646755221 is about 864.7952876294.

It can be divided in two parts, 64675 and 5221, that added together give a palindrome (69896).

The spelling of 646755221 in words is "six hundred forty-six million, seven hundred fifty-five thousand, two hundred twenty-one".