643188816 has 80 divisors (see below), whose sum is σ = 1853065920. Its totient is φ = 213598080.

The previous prime is 643188803. The next prime is 643188827. The reversal of 643188816 is 618881346.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 119626 + ... + 124886.

It is an arithmetic number, because the mean of its divisors is an integer number (23163324).

Almost surely, 2^643188816 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 643188816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (926532960).

643188816 is an abundant number, since it is smaller than the sum of its proper divisors (1209877104).

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

643188816 is a wasteful number, since it uses less digits than its factorization.

643188816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5561 (or 5549 counting only the distinct ones).

The product of its digits is 221184, while the sum is 45.

The square root of 643188816 is about 25361.1674810132. The cubic root of 643188816 is about 863.2027754187.

The spelling of 643188816 in words is "six hundred forty-three million, one hundred eighty-eight thousand, eight hundred sixteen".