643406868 has 96 divisors (see below), whose sum is σ = 1802008320. Its totient is φ = 197354880.

The previous prime is 643406867. The next prime is 643406879. The reversal of 643406868 is 868604346.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643406867) 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 31 ways as a sum of consecutive naturals, for example, 683278 + ... + 684218.

It is an arithmetic number, because the mean of its divisors is an integer number (18770920).

Almost surely, 2^643406868 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 643406868, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (901004160).

643406868 is an abundant number, since it is smaller than the sum of its proper divisors (1158601452).

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

643406868 is a wasteful number, since it uses less digits than its factorization.

643406868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1454 (or 1446 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 45.

The square root of 643406868 is about 25365.4660513068. The cubic root of 643406868 is about 863.3003112281.

The spelling of 643406868 in words is "six hundred forty-three million, four hundred six thousand, eight hundred sixty-eight".