643600440 has 192 divisors, whose sum is σ = 2410536960. Its totient is φ = 145877760.

The previous prime is 643600423. The next prime is 643600453. The reversal of 643600440 is 44006346.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 319035 + ... + 321045.

It is an arithmetic number, because the mean of its divisors is an integer number (12554880).

Almost surely, 2^643600440 is an apocalyptic number.

643600440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643600440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1205268480).

643600440 is an abundant number, since it is smaller than the sum of its proper divisors (1766936520).

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

643600440 is a wasteful number, since it uses less digits than its factorization.

643600440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2162 (or 2155 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 27.

The square root of 643600440 is about 25369.2814245891. The cubic root of 643600440 is about 863.3868785415.

Adding to 643600440 its reverse (44006346), we get a palindrome (687606786).

The spelling of 643600440 in words is "six hundred forty-three million, six hundred thousand, four hundred forty".