643784904 has 384 divisors, whose sum is σ = 2276352000. Its totient is φ = 160123392.

The previous prime is 643784887. The next prime is 643784909. The reversal of 643784904 is 409487346.

It is a self number, because there is not a number n which added to its sum of digits gives 643784904.

It is not an unprimeable number, because it can be changed into a prime (643784909) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 8149137 + ... + 8149215.

It is an arithmetic number, because the mean of its divisors is an integer number (5928000).

Almost surely, 2^643784904 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 643784904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1138176000).

643784904 is an abundant number, since it is smaller than the sum of its proper divisors (1632567096).

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

643784904 is a wasteful number, since it uses less digits than its factorization.

643784904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177 (or 170 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 45.

The square root of 643784904 is about 25372.9167420697. The cubic root of 643784904 is about 863.4693565170.

The spelling of 643784904 in words is "six hundred forty-three million, seven hundred eighty-four thousand, nine hundred four".