639280 has 40 divisors (see below), whose sum is σ = 1522224. Its totient is φ = 249600.

The previous prime is 639269. The next prime is 639299. The reversal of 639280 is 82936.

It is a tau number, because it is divible by the number of its divisors (40).

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 7 ways as a sum of consecutive naturals, for example, 4815 + ... + 4945.

2⁶³⁹²⁸⁰ 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 639280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (761112).

639280 is an abundant number, since it is smaller than the sum of its proper divisors (882944).

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

639280 is a wasteful number, since it uses less digits than its factorization.

639280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205 (or 199 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 639280 is about 799.5498733663. The cubic root of 639280 is about 86.1450589546.

It can be divided in two parts, 639 and 280, that added together give a palindrome (919).

The spelling of 639280 in words is "six hundred thirty-nine thousand, two hundred eighty".