6440664438 has 48 divisors (see below), whose sum is σ = 15912239616. Its totient is φ = 1865168640.

The previous prime is 6440664431. The next prime is 6440664449. The reversal of 6440664438 is 8344660446.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 6440664393 and 6440664402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6440664431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 805558 + ... + 813513.

It is an arithmetic number, because the mean of its divisors is an integer number (331504992).

Almost surely, 2^6440664438 is an apocalyptic number.

6440664438 is an abundant number, since it is smaller than the sum of its proper divisors (9471575178).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6440664438 is a wasteful number, since it uses less digits than its factorization.

6440664438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1619109 (or 1619106 counting only the distinct ones).

The product of its (nonzero) digits is 1327104, while the sum is 45.

The square root of 6440664438 is about 80253.7503048923. The cubic root of 6440664438 is about 1860.5594761638.

The spelling of 6440664438 in words is "six billion, four hundred forty million, six hundred sixty-four thousand, four hundred thirty-eight".