643769984 has 64 divisors (see below), whose sum is σ = 1506768480. Its totient is φ = 270105600.

The previous prime is 643769947. The next prime is 643769999. The reversal of 643769984 is 489967346.

It is a tau number, because it is divible by the number of its divisors (64).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 719 + ... + 35889.

Almost surely, 2^643769984 is an apocalyptic number.

643769984 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 643769984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (753384240).

643769984 is an abundant number, since it is smaller than the sum of its proper divisors (862998496).

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

643769984 is a wasteful number, since it uses less digits than its factorization.

643769984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35209 (or 35197 counting only the distinct ones).

The product of its digits is 7838208, while the sum is 56.

The square root of 643769984 is about 25372.6227260802. The cubic root of 643769984 is about 863.4626860373.

The spelling of 643769984 in words is "six hundred forty-three million, seven hundred sixty-nine thousand, nine hundred eighty-four".