639717 has 16 divisors (see below), whose sum is σ = 940800. Its totient is φ = 384192.

The previous prime is 639713. The next prime is 639719. The reversal of 639717 is 717936.

639717 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 639717 - 2² = 639713 is a prime.

639717 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639713) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1659 + ... + 2007.

It is an arithmetic number, because the mean of its divisors is an integer number (58800).

2⁶³⁹⁷¹⁷ is an apocalyptic number.

It is an amenable number.

639717 is a deficient number, since it is larger than the sum of its proper divisors (301083).

639717 is a wasteful number, since it uses less digits than its factorization.

639717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 412.

The product of its digits is 7938, while the sum is 33.

The square root of 639717 is about 799.8231054427. The cubic root of 639717 is about 86.1646835407.

It can be divided in two parts, 63 and 9717, that multiplied together give a triangular number (612171 = T₁₁₀₆).

The spelling of 639717 in words is "six hundred thirty-nine thousand, seven hundred seventeen".