639240 has 64 divisors (see below), whose sum is σ = 2194560. Its totient is φ = 145920.

The previous prime is 639211. The next prime is 639253. The reversal of 639240 is 42936.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nialpdrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 639240.

It is an unprimeable number.

639240 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 15 ways as a sum of consecutive naturals, for example, 460 + ... + 1220.

It is an arithmetic number, because the mean of its divisors is an integer number (34290).

2⁶³⁹²⁴⁰ is an apocalyptic number.

639240 is a gapful number since it is divisible by the number (60) 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 639240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1097280).

639240 is an abundant number, since it is smaller than the sum of its proper divisors (1555320).

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

639240 is a wasteful number, since it uses less digits than its factorization.

639240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782 (or 778 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 24.

The square root of 639240 is about 799.5248589006. The cubic root of 639240 is about 86.1432622071.

The spelling of 639240 in words is "six hundred thirty-nine thousand, two hundred forty".