6643432406221 has 16 divisors (see below), whose sum is σ = 7485227487360. Its totient is φ = 5850296020800.

The previous prime is 6643432406207. The next prime is 6643432406243. The reversal of 6643432406221 is 1226042343466.

It is a cyclic number.

It is not a de Polignac number, because 6643432406221 - 2²³ = 6643424017613 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 (6643436406221) 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, 29199130 + ... + 29425771.

It is an arithmetic number, because the mean of its divisors is an integer number (467826717960).

Almost surely, 2^{6643432406221} is an apocalyptic number.

It is an amenable number.

6643432406221 is a deficient number, since it is larger than the sum of its proper divisors (841795081139).

6643432406221 is a wasteful number, since it uses less digits than its factorization.

6643432406221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58625316.

The product of its (nonzero) digits is 995328, while the sum is 43.

Adding to 6643432406221 its reverse (1226042343466), we get a palindrome (7869474749687).

The spelling of 6643432406221 in words is "six trillion, six hundred forty-three billion, four hundred thirty-two million, four hundred six thousand, two hundred twenty-one".