643792640 has 72 divisors (see below), whose sum is σ = 1556080848. Its totient is φ = 255180800.

The previous prime is 643792631. The next prime is 643792673. The reversal of 643792640 is 46297346.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 142415 + ... + 146865.

It is an arithmetic number, because the mean of its divisors is an integer number (21612234).

Almost surely, 2^643792640 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 643792640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (778040424).

643792640 is an abundant number, since it is smaller than the sum of its proper divisors (912288208).

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

643792640 is a wasteful number, since it uses less digits than its factorization.

643792640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4585 (or 4571 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 41.

The square root of 643792640 is about 25373.0691876249. The cubic root of 643792640 is about 863.4728151112.

The spelling of 643792640 in words is "six hundred forty-three million, seven hundred ninety-two thousand, six hundred forty".