643264 has 42 divisors (see below), whose sum is σ = 1404620. Its totient is φ = 291456.

The previous prime is 643243. The next prime is 643273. The reversal of 643264 is 462346.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 27957 + ... + 27979.

2⁶⁴³²⁶⁴ is an apocalyptic number.

643264 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 643264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (702310).

643264 is an abundant number, since it is smaller than the sum of its proper divisors (761356).

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

643264 is a wasteful number, since it uses less digits than its factorization.

643264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77 (or 44 counting only the distinct ones).

The product of its digits is 3456, while the sum is 25.

The square root of 643264 is about 802.0374056115. The cubic root of 643264 is about 86.3236408108.

The spelling of 643264 in words is "six hundred forty-three thousand, two hundred sixty-four".