6445221 has 16 divisors (see below), whose sum is σ = 9279360. Its totient is φ = 3967040.

The previous prime is 6445217. The next prime is 6445223. The reversal of 6445221 is 1225446.

It is not a de Polignac number, because 6445221 - 2² = 6445217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6445191 and 6445200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6445223) 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, 391 + ... + 3611.

It is an arithmetic number, because the mean of its divisors is an integer number (579960).

Almost surely, 2^6445221 is an apocalyptic number.

It is an amenable number.

6445221 is a deficient number, since it is larger than the sum of its proper divisors (2834139).

6445221 is a wasteful number, since it uses less digits than its factorization.

6445221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3276.

The product of its digits is 1920, while the sum is 24.

The square root of 6445221 is about 2538.7439807905. The cubic root of 6445221 is about 186.0998134640.

It can be divided in two parts, 6445 and 221, that added together give a palindrome (6666).

The spelling of 6445221 in words is "six million, four hundred forty-five thousand, two hundred twenty-one".