639903 has 8 divisors (see below), whose sum is σ = 930816. Its totient is φ = 387800.

The previous prime is 639857. The next prime is 639907. The reversal of 639903 is 309936.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 639903 - 2⁶ = 639839 is a prime.

639903 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639907) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9663 + ... + 9728.

It is an arithmetic number, because the mean of its divisors is an integer number (116352).

2⁶³⁹⁹⁰³ is an apocalyptic number.

639903 is a deficient number, since it is larger than the sum of its proper divisors (290913).

639903 is a wasteful number, since it uses less digits than its factorization.

639903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19405.

The product of its (nonzero) digits is 4374, while the sum is 30.

The square root of 639903 is about 799.9393727027. The cubic root of 639903 is about 86.1730336279.

The spelling of 639903 in words is "six hundred thirty-nine thousand, nine hundred three".