639556 has 12 divisors (see below), whose sum is σ = 1125180. Its totient is φ = 318080.

The previous prime is 639547. The next prime is 639563. The reversal of 639556 is 655936.

It can be written as a sum of positive squares in 2 ways, for example, as 260100 + 379456 = 510^2 + 616^2 .

It is a nialpdrome in base 15.

It is an unprimeable number.

639556 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 3 ways as a sum of consecutive naturals, for example, 840 + ... + 1408.

It is an arithmetic number, because the mean of its divisors is an integer number (93765).

2⁶³⁹⁵⁵⁶ is an apocalyptic number.

It is an amenable number.

639556 is a deficient number, since it is larger than the sum of its proper divisors (485624).

639556 is a wasteful number, since it uses less digits than its factorization.

639556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 854 (or 852 counting only the distinct ones).

The product of its digits is 24300, while the sum is 34.

The square root of 639556 is about 799.7224518544. The cubic root of 639556 is about 86.1574544701.

The spelling of 639556 in words is "six hundred thirty-nine thousand, five hundred fifty-six".