639256 has 8 divisors (see below), whose sum is σ = 1198620. Its totient is φ = 319624.

The previous prime is 639253. The next prime is 639257. The reversal of 639256 is 652936.

It is a tau number, because it is divible by the number of its divisors (8).

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639253) by changing a digit.

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 as a sum of consecutive naturals, namely, 39946 + ... + 39961.

2⁶³⁹²⁵⁶ is an apocalyptic number.

It is an amenable number.

639256 is a deficient number, since it is larger than the sum of its proper divisors (559364).

639256 is a wasteful number, since it uses less digits than its factorization.

639256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79913 (or 79909 counting only the distinct ones).

The product of its digits is 9720, while the sum is 31.

The square root of 639256 is about 799.5348647808. The cubic root of 639256 is about 86.1439809151.

The spelling of 639256 in words is "six hundred thirty-nine thousand, two hundred fifty-six".