6443531640 has 256 divisors, whose sum is σ = 26435404800. Its totient is φ = 1359493632.

The previous prime is 6443531569. The next prime is 6443531651. The reversal of 6443531640 is 461353446.

6443531640 is a `hidden beast` number, since 6 + 4 + 4 + 3 + 5 + 3 + 1 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 6443531595 and 6443531604.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 65499 + ... + 131061.

It is an arithmetic number, because the mean of its divisors is an integer number (103263300).

Almost surely, 2^6443531640 is an apocalyptic number.

6443531640 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 6443531640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13217702400).

6443531640 is an abundant number, since it is smaller than the sum of its proper divisors (19991873160).

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

6443531640 is a wasteful number, since it uses less digits than its factorization.

6443531640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65603 (or 65593 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 36.

The square root of 6443531640 is about 80271.6116693816. The cubic root of 6443531640 is about 1860.8355247244.

The spelling of 6443531640 in words is "six billion, four hundred forty-three million, five hundred thirty-one thousand, six hundred forty".