6521000640 has 448 divisors, whose sum is σ = 27177431040. Its totient is φ = 1283420160.

The previous prime is 6521000599. The next prime is 6521000693. The reversal of 6521000640 is 460001256.

It is a tau number, because it is divible by the number of its divisors (448).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 6521000640.

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, 1402159 + ... + 1406801.

Almost surely, 2^6521000640 is an apocalyptic number.

6521000640 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 6521000640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13588715520).

6521000640 is an abundant number, since it is smaller than the sum of its proper divisors (20656430400).

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

6521000640 is a wasteful number, since it uses less digits than its factorization.

6521000640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4700 (or 4690 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 6521000640 is about 80752.7128956049. The cubic root of 6521000640 is about 1868.2632926901.

Adding to 6521000640 its reverse (460001256), we get a palindrome (6981001896).

The spelling of 6521000640 in words is "six billion, five hundred twenty-one million, six hundred forty", and thus it is an aban number.