643280 has 80 divisors (see below), whose sum is σ = 1767744. Its totient is φ = 215040.

The previous prime is 643273. The next prime is 643301. The reversal of 643280 is 82346.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643280.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14939 + ... + 14981.

2⁶⁴³²⁸⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (883872).

643280 is an abundant number, since it is smaller than the sum of its proper divisors (1124464).

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

643280 is a wasteful number, since it uses less digits than its factorization.

643280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84 (or 78 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 643280 is about 802.0473801466. The cubic root of 643280 is about 86.3243565184.

The spelling of 643280 in words is "six hundred forty-three thousand, two hundred eighty".