6389720640 has 420 divisors, whose sum is σ = 24173335956. Its totient is φ = 1601814528.

The previous prime is 6389720629. The next prime is 6389720663. The reversal of 6389720640 is 460279836.

6389720640 is a `hidden beast` number, since 638 + 9 + 7 + 2 + 0 + 6 + 4 + 0 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 14017536 + 6375703104 = 3744^2 + 79848^2 .

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 (17) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 7490454 + ... + 7491306.

Almost surely, 2^6389720640 is an apocalyptic number.

6389720640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6389720640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12086667978).

6389720640 is an abundant number, since it is smaller than the sum of its proper divisors (17783615316).

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

6389720640 is a wasteful number, since it uses less digits than its factorization.

6389720640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 916 (or 880 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 45.

The square root of 6389720640 is about 79935.7281820839. The cubic root of 6389720640 is about 1855.6409890717.

The spelling of 6389720640 in words is "six billion, three hundred eighty-nine million, seven hundred twenty thousand, six hundred forty".