6444873621 has 20 divisors (see below), whose sum is σ = 10193854572. Its totient is φ = 4043841408.

The previous prime is 6444873613. The next prime is 6444873661. The reversal of 6444873621 is 1263784446.

It can be written as a sum of positive squares in 2 ways, for example, as 5823368721 + 621504900 = 76311^2 + 24930^2 .

It is not a de Polignac number, because 6444873621 - 2³ = 6444873613 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6444873661) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2338810 + ... + 2341563.

Almost surely, 2^6444873621 is an apocalyptic number.

It is an amenable number.

6444873621 is a deficient number, since it is larger than the sum of its proper divisors (3748980951).

6444873621 is a wasteful number, since it uses less digits than its factorization.

6444873621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4680402 (or 4680393 counting only the distinct ones).

The product of its digits is 774144, while the sum is 45.

The square root of 6444873621 is about 80279.9702354205. The cubic root of 6444873621 is about 1860.9646998784.

The spelling of 6444873621 in words is "six billion, four hundred forty-four million, eight hundred seventy-three thousand, six hundred twenty-one".