643608404640 has 768 divisors, whose sum is σ = 2591834112000. Its totient is φ = 148084899840.

The previous prime is 643608404629. The next prime is 643608404669. The reversal of 643608404640 is 46404806346.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 43248721 + ... + 43263599.

It is an arithmetic number, because the mean of its divisors is an integer number (3374784000).

Almost surely, 2^643608404640 is an apocalyptic number.

643608404640 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 643608404640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1295917056000).

643608404640 is an abundant number, since it is smaller than the sum of its proper divisors (1948225707360).

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

643608404640 is a wasteful number, since it uses less digits than its factorization.

643608404640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14970 (or 14956 counting only the distinct ones).

The product of its (nonzero) digits is 1327104, while the sum is 45.

The spelling of 643608404640 in words is "six hundred forty-three billion, six hundred eight million, four hundred four thousand, six hundred forty".