643623984 has 90 divisors (see below), whose sum is σ = 1861632708. Its totient is φ = 207576000.

The previous prime is 643623983. The next prime is 643624001. The reversal of 643623984 is 489326346.

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

It is not an unprimeable number, because it can be changed into a prime (643623983) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 136059 + ... + 140709.

Almost surely, 2^643623984 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 643623984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (930816354).

643623984 is an abundant number, since it is smaller than the sum of its proper divisors (1218008724).

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

643623984 is a wasteful number, since it uses less digits than its factorization.

643623984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4727 (or 4687 counting only the distinct ones).

The product of its digits is 746496, while the sum is 45.

The square root of 643623984 is about 25369.7454461017. The cubic root of 643623984 is about 863.3974064672.

The spelling of 643623984 in words is "six hundred forty-three million, six hundred twenty-three thousand, nine hundred eighty-four".