6439623840 has 144 divisors (see below), whose sum is σ = 23665686408. Its totient is φ = 1585133568.

The previous prime is 6439623821. The next prime is 6439623857. The reversal of 6439623840 is 483269346.

It can be written as a sum of positive squares in 4 ways, for example, as 4977020304 + 1462603536 = 70548^2 + 38244^2 .

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 153279 + ... + 190718.

Almost surely, 2^6439623840 is an apocalyptic number.

6439623840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

6439623840 is an abundant number, since it is smaller than the sum of its proper divisors (17226062568).

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

6439623840 is a wasteful number, since it uses less digits than its factorization.

6439623840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 344031 (or 344020 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 45.

The square root of 6439623840 is about 80247.2668693458. The cubic root of 6439623840 is about 1860.4592691760.

The spelling of 6439623840 in words is "six billion, four hundred thirty-nine million, six hundred twenty-three thousand, eight hundred forty".