643944384 has 56 divisors (see below), whose sum is σ = 1893082320. Its totient is φ = 214647552.

The previous prime is 643944383. The next prime is 643944397. The reversal of 643944384 is 483449346.

It is a happy number.

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 (643944383) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 184599 + ... + 188054.

Almost surely, 2^643944384 is an apocalyptic number.

643944384 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

643944384 is an abundant number, since it is smaller than the sum of its proper divisors (1249137936).

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

643944384 is a wasteful number, since it uses less digits than its factorization.

643944384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372674 (or 372658 counting only the distinct ones).

The product of its digits is 995328, while the sum is 45.

The square root of 643944384 is about 25376.0592685310. The cubic root of 643944384 is about 863.5406508902.

The spelling of 643944384 in words is "six hundred forty-three million, nine hundred forty-four thousand, three hundred eighty-four".