643866624 has 224 divisors, whose sum is σ = 1981687680. Its totient is φ = 206438400.

The previous prime is 643866611. The next prime is 643866667. The reversal of 643866624 is 426668346.

It is a super-3 number, since 3×643866624³ (a number of 27 digits) contains 333 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 643866624.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9068509 + ... + 9068579.

It is an arithmetic number, because the mean of its divisors is an integer number (8846820).

Almost surely, 2^643866624 is an apocalyptic number.

643866624 is a gapful number since it is divisible by the number (64) 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 643866624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (990843840).

643866624 is an abundant number, since it is smaller than the sum of its proper divisors (1337821056).

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

643866624 is an equidigital number, since it uses as much as digits as its factorization.

643866624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147 (or 117 counting only the distinct ones).

The product of its digits is 995328, while the sum is 45.

The square root of 643866624 is about 25374.5270694845. The cubic root of 643866624 is about 863.5058903189.

The spelling of 643866624 in words is "six hundred forty-three million, eight hundred sixty-six thousand, six hundred twenty-four".