6421947840 has 896 divisors, whose sum is σ = 28968192000. Its totient is φ = 1327656960.

The previous prime is 6421947823. The next prime is 6421947859. The reversal of 6421947840 is 487491246.

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

It is a zygodrome in base 14.

It is a congruent number.

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 127 ways as a sum of consecutive naturals, for example, 32598622 + ... + 32598818.

Almost surely, 2^6421947840 is an apocalyptic number.

6421947840 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 6421947840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14484096000).

6421947840 is an abundant number, since it is smaller than the sum of its proper divisors (22546244160).

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

6421947840 is a wasteful number, since it uses less digits than its factorization.

6421947840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 45.

The square root of 6421947840 is about 80137.0565968079. The cubic root of 6421947840 is about 1858.7554629841.

The spelling of 6421947840 in words is "six billion, four hundred twenty-one million, nine hundred forty-seven thousand, eight hundred forty".