6443229721 has 4 divisors (see below), whose sum is σ = 6822243252. Its totient is φ = 6064216192.

The previous prime is 6443229719. The next prime is 6443229731. The reversal of 6443229721 is 1279223446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4062277696 + 2380952025 = 63736^2 + 48795^2 .

It is a cyclic number.

It is not a de Polignac number, because 6443229721 - 2¹ = 6443229719 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6443229731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 189506740 + ... + 189506773.

It is an arithmetic number, because the mean of its divisors is an integer number (1705560813).

Almost surely, 2^6443229721 is an apocalyptic number.

It is an amenable number.

6443229721 is a deficient number, since it is larger than the sum of its proper divisors (379013531).

6443229721 is a wasteful number, since it uses less digits than its factorization.

6443229721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 379013530.

The product of its digits is 145152, while the sum is 40.

The square root of 6443229721 is about 80269.7310385428. The cubic root of 6443229721 is about 1860.8064604158.

The spelling of 6443229721 in words is "six billion, four hundred forty-three million, two hundred twenty-nine thousand, seven hundred twenty-one".