643764880 has 80 divisors (see below), whose sum is σ = 1636752384. Its totient is φ = 233533440.

The previous prime is 643764851. The next prime is 643764883. The reversal of 643764880 is 88467346.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 643764880.

It is not an unprimeable number, because it can be changed into a prime (643764883) 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, 591697 + ... + 592783.

Almost surely, 2^643764880 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 643764880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (818376192).

643764880 is an abundant number, since it is smaller than the sum of its proper divisors (992987504).

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

643764880 is a wasteful number, since it uses less digits than its factorization.

643764880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1784 (or 1778 counting only the distinct ones).

The product of its (nonzero) digits is 774144, while the sum is 46.

The square root of 643764880 is about 25372.5221450293. The cubic root of 643764880 is about 863.4604041016.

It can be divided in two parts, 6437 and 64880, that added together give a palindrome (71317).

The spelling of 643764880 in words is "six hundred forty-three million, seven hundred sixty-four thousand, eight hundred eighty".