643399680 has 512 divisors, whose sum is σ = 2717867520. Its totient is φ = 125829120.

The previous prime is 643399643. The next prime is 643399693. The reversal of 643399680 is 86993346.

It is a tau number, because it is divible by the number of its divisors (512).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 37847032 + ... + 37847048.

It is an arithmetic number, because the mean of its divisors is an integer number (5308335).

Almost surely, 2^643399680 is an apocalyptic number.

643399680 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 643399680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1358933760).

643399680 is an abundant number, since it is smaller than the sum of its proper divisors (2074467840).

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

643399680 is a wasteful number, since it uses less digits than its factorization.

643399680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73 (or 45 counting only the distinct ones).

The product of its (nonzero) digits is 839808, while the sum is 48.

The square root of 643399680 is about 25365.3243622076. The cubic root of 643399680 is about 863.2970963491.

The spelling of 643399680 in words is "six hundred forty-three million, three hundred ninety-nine thousand, six hundred eighty".