643648896 has 128 divisors (see below), whose sum is σ = 2072476800. Its totient is φ = 195033600.

The previous prime is 643648891. The next prime is 643648903. The reversal of 643648896 is 698846346.

It is a tau number, because it is divible by the number of its divisors (128).

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643648891) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 29551 + ... + 46481.

It is an arithmetic number, because the mean of its divisors is an integer number (16191225).

Almost surely, 2^643648896 is an apocalyptic number.

643648896 is a gapful number since it is divisible by the number (66) 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 643648896, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1036238400).

643648896 is an abundant number, since it is smaller than the sum of its proper divisors (1428827904).

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

643648896 is a wasteful number, since it uses less digits than its factorization.

643648896 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16965 (or 16947 counting only the distinct ones).

The product of its digits is 5971968, while the sum is 54.

The square root of 643648896 is about 25370.2364198681. The cubic root of 643648896 is about 863.4085458277.

The spelling of 643648896 in words is "six hundred forty-three million, six hundred forty-eight thousand, eight hundred ninety-six".