6646402221 has 4 divisors (see below), whose sum is σ = 8861869632. Its totient is φ = 4430934812.

The previous prime is 6646402187. The next prime is 6646402271. The reversal of 6646402221 is 1222046466.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6646402221 - 2⁹ = 6646401709 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6646402271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1107733701 + ... + 1107733706.

It is an arithmetic number, because the mean of its divisors is an integer number (2215467408).

Almost surely, 2^6646402221 is an apocalyptic number.

It is an amenable number.

6646402221 is a deficient number, since it is larger than the sum of its proper divisors (2215467411).

6646402221 is a wasteful number, since it uses less digits than its factorization.

6646402221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2215467410.

The product of its (nonzero) digits is 27648, while the sum is 33.

The square root of 6646402221 is about 81525.4697686557. The cubic root of 6646402221 is about 1880.1631649731.

Adding to 6646402221 its reverse (1222046466), we get a palindrome (7868448687).

The spelling of 6646402221 in words is "six billion, six hundred forty-six million, four hundred two thousand, two hundred twenty-one".