6503440644 has 96 divisors (see below), whose sum is σ = 18097511040. Its totient is φ = 2012304384.

The previous prime is 6503440579. The next prime is 6503440651. The reversal of 6503440644 is 4460443056.

6503440644 is a `hidden beast` number, since 6 + 5 + 0 + 3 + 4 + 4 + 0 + 644 = 666.

It is a super-2 number, since 2×6503440644² = 84589480420062269472, which contains 22 as substring.

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 = 6503440599 and 6503440608.

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 31 ways as a sum of consecutive naturals, for example, 109767 + ... + 158289.

It is an arithmetic number, because the mean of its divisors is an integer number (188515740).

Almost surely, 2^6503440644 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 6503440644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9048755520).

6503440644 is an abundant number, since it is smaller than the sum of its proper divisors (11594070396).

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

6503440644 is a wasteful number, since it uses less digits than its factorization.

6503440644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48626 (or 48618 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 36.

The square root of 6503440644 is about 80643.9126282945. The cubic root of 6503440644 is about 1866.5848085844.

The spelling of 6503440644 in words is "six billion, five hundred three million, four hundred forty thousand, six hundred forty-four".