643918464 has 256 divisors, whose sum is σ = 2226048000. Its totient is φ = 179407872.

The previous prime is 643918427. The next prime is 643918477. The reversal of 643918464 is 464819346.

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

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 31 ways as a sum of consecutive naturals, for example, 1039947 + ... + 1040565.

It is an arithmetic number, because the mean of its divisors is an integer number (8695500).

Almost surely, 2^643918464 is an apocalyptic number.

643918464 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 643918464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1113024000).

643918464 is an abundant number, since it is smaller than the sum of its proper divisors (1582129536).

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

643918464 is a wasteful number, since it uses less digits than its factorization.

643918464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 692 (or 674 counting only the distinct ones).

The product of its digits is 497664, while the sum is 45.

The square root of 643918464 is about 25375.5485457950. The cubic root of 643918464 is about 863.5290643440.

The spelling of 643918464 in words is "six hundred forty-three million, nine hundred eighteen thousand, four hundred sixty-four".