643677840 has 320 divisors, whose sum is σ = 2425678080. Its totient is φ = 157883904.

The previous prime is 643677833. The next prime is 643677841. The reversal of 643677840 is 48776346.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (643677841) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2274339 + ... + 2274621.

It is an arithmetic number, because the mean of its divisors is an integer number (7580244).

Almost surely, 2^643677840 is an apocalyptic number.

643677840 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 643677840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1212839040).

643677840 is an abundant number, since it is smaller than the sum of its proper divisors (1782000240).

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

643677840 is a wasteful number, since it uses less digits than its factorization.

643677840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330 (or 306 counting only the distinct ones).

The product of its (nonzero) digits is 677376, while the sum is 45.

The square root of 643677840 is about 25370.8068456642. The cubic root of 643677840 is about 863.4214877295.

The spelling of 643677840 in words is "six hundred forty-three million, six hundred seventy-seven thousand, eight hundred forty".