6445581440 has 64 divisors (see below), whose sum is σ = 15473808000. Its totient is φ = 2567384064.

The previous prime is 6445581397. The next prime is 6445581497. The reversal of 6445581440 is 441855446.

It is a tau number, because it is divible by the number of its divisors (64).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 131891 + ... + 174029.

It is an arithmetic number, because the mean of its divisors is an integer number (241778250).

Almost surely, 2^6445581440 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6445581440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7736904000).

6445581440 is an abundant number, since it is smaller than the sum of its proper divisors (9028226560).

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

6445581440 is a wasteful number, since it uses less digits than its factorization.

6445581440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42397 (or 42385 counting only the distinct ones).

The product of its (nonzero) digits is 307200, while the sum is 41.

The square root of 6445581440 is about 80284.3785552333. The cubic root of 6445581440 is about 1861.0328252357.

The spelling of 6445581440 in words is "six billion, four hundred forty-five million, five hundred eighty-one thousand, four hundred forty".