646420221 has 48 divisors (see below), whose sum is σ = 999358464. Its totient is φ = 401762592.

The previous prime is 646420207. The next prime is 646420231. The reversal of 646420221 is 122024646.

It is not a de Polignac number, because 646420221 - 2⁶ = 646420157 is a prime.

It is a super-3 number, since 3×646420221³ (a number of 27 digits) contains 333 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646420231) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1761180 + ... + 1761546.

It is an arithmetic number, because the mean of its divisors is an integer number (20819968).

Almost surely, 2^646420221 is an apocalyptic number.

It is an amenable number.

646420221 is a deficient number, since it is larger than the sum of its proper divisors (352938243).

646420221 is a wasteful number, since it uses less digits than its factorization.

646420221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 590 (or 587 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

The square root of 646420221 is about 25424.7953974068. The cubic root of 646420221 is about 864.6459490821.

Adding to 646420221 its reverse (122024646), we get a palindrome (768444867).

The spelling of 646420221 in words is "six hundred forty-six million, four hundred twenty thousand, two hundred twenty-one".