643541920 has 96 divisors (see below), whose sum is σ = 1742888448. Its totient is φ = 219967488.

The previous prime is 643541897. The next prime is 643541947. The reversal of 643541920 is 29145346.

It is a happy number.

643541920 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 484297 + ... + 485623.

It is an arithmetic number, because the mean of its divisors is an integer number (18155088).

Almost surely, 2^643541920 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 643541920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (871444224).

643541920 is an abundant number, since it is smaller than the sum of its proper divisors (1099346528).

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

643541920 is a wasteful number, since it uses less digits than its factorization.

643541920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1782 (or 1774 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 643541920 is about 25368.1280349970. The cubic root of 643541920 is about 863.3607096494.

The spelling of 643541920 in words is "six hundred forty-three million, five hundred forty-one thousand, nine hundred twenty".