639220 has 24 divisors (see below), whose sum is σ = 1387008. Its totient is φ = 247200.

The previous prime is 639211. The next prime is 639253. The reversal of 639220 is 22936.

It is a junction number, because it is equal to n+sod(n) for n = 639191 and 639200.

It is a congruent number.

It is an unprimeable number.

639220 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 105 + ... + 1135.

It is an arithmetic number, because the mean of its divisors is an integer number (57792).

2⁶³⁹²²⁰ 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 639220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (693504).

639220 is an abundant number, since it is smaller than the sum of its proper divisors (747788).

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

639220 is a wasteful number, since it uses less digits than its factorization.

639220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1071 (or 1069 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 639220 is about 799.5123513743. The cubic root of 639220 is about 86.1423638053.

The spelling of 639220 in words is "six hundred thirty-nine thousand, two hundred twenty".