6444388021 has 8 divisors (see below), whose sum is σ = 6457316760. Its totient is φ = 6431473152.

The previous prime is 6444387979. The next prime is 6444388141. The reversal of 6444388021 is 1208834446.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 30140100 + 6414247921 = 5490^2 + 80089^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6444388021 - 2¹¹ = 6444385973 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 (6444388921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1513131 + ... + 1517383.

It is an arithmetic number, because the mean of its divisors is an integer number (807164595).

Almost surely, 2^6444388021 is an apocalyptic number.

It is an amenable number.

6444388021 is a deficient number, since it is larger than the sum of its proper divisors (12928739).

6444388021 is a wasteful number, since it uses less digits than its factorization.

6444388021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6935.

The product of its (nonzero) digits is 147456, while the sum is 40.

The square root of 6444388021 is about 80276.9457627780. The cubic root of 6444388021 is about 1860.9179595176.

The spelling of 6444388021 in words is "six billion, four hundred forty-four million, three hundred eighty-eight thousand, twenty-one".