6644249856 has 324 divisors, whose sum is σ = 20737213952. Its totient is φ = 2121541632.

The previous prime is 6644249831. The next prime is 6644249863. The reversal of 6644249856 is 6589424466.

6644249856 is a `hidden beast` number, since 6 + 64 + 42 + 498 + 56 = 666.

It is a tau number, because it is divible by the number of its divisors (324).

It is a super-2 number, since 2×6644249856² = 88292112297912041472, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

Its product of digits (9953280) is a multiple of the sum of its prime factors (216).

It is a congruent number.

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 35 ways as a sum of consecutive naturals, for example, 52316865 + ... + 52316991.

Almost surely, 2^6644249856 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 6644249856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10368606976).

6644249856 is an abundant number, since it is smaller than the sum of its proper divisors (14092964096).

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

6644249856 is an equidigital number, since it uses as much as digits as its factorization.

6644249856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216 (or 161 counting only the distinct ones).

The product of its digits is 9953280, while the sum is 54.

The square root of 6644249856 is about 81512.2681318585. The cubic root of 6644249856 is about 1879.9601862702.

The spelling of 6644249856 in words is "six billion, six hundred forty-four million, two hundred forty-nine thousand, eight hundred fifty-six".