643643264 has 64 divisors (see below), whose sum is σ = 1431492480. Its totient is φ = 285734400.

The previous prime is 643643237. The next prime is 643643267. The reversal of 643643264 is 462346346.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643643267) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55229 + ... + 65859.

It is an arithmetic number, because the mean of its divisors is an integer number (22367070).

Almost surely, 2^643643264 is an apocalyptic number.

643643264 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 643643264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (715746240).

643643264 is an abundant number, since it is smaller than the sum of its proper divisors (787849216).

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

643643264 is a wasteful number, since it uses less digits than its factorization.

643643264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10699 (or 10687 counting only the distinct ones).

The product of its digits is 248832, while the sum is 38.

The square root of 643643264 is about 25370.1254234188. The cubic root of 643643264 is about 863.4060275131.

The spelling of 643643264 in words is "six hundred forty-three million, six hundred forty-three thousand, two hundred sixty-four".