6440646240 has 432 divisors, whose sum is σ = 26268710832. Its totient is φ = 1431779328.

The previous prime is 6440646209. The next prime is 6440646281. The reversal of 6440646240 is 426460446.

It is a happy number.

6440646240 is a `hidden beast` number, since 6 + 4 + 4 + 0 + 646 + 2 + 4 + 0 = 666.

It is a super-2 number, since 2×6440646240² = 82963847977652275200, 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 = 6440646195 and 6440646204.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2609487 + ... + 2611953.

It is an arithmetic number, because the mean of its divisors is an integer number (60807201).

Almost surely, 2^6440646240 is an apocalyptic number.

6440646240 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 6440646240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13134355416).

6440646240 is an abundant number, since it is smaller than the sum of its proper divisors (19828064592).

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

6440646240 is a wasteful number, since it uses less digits than its factorization.

6440646240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2539 (or 2521 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 36.

The square root of 6440646240 is about 80253.6369269331. The cubic root of 6440646240 is about 1860.5577238346.

The spelling of 6440646240 in words is "six billion, four hundred forty million, six hundred forty-six thousand, two hundred forty".