639718 has 8 divisors (see below), whose sum is σ = 963000. Its totient is φ = 318720.

The previous prime is 639713. The next prime is 639719. The reversal of 639718 is 817936.

639718 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a congruent number.

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

639718 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 3 ways as a sum of consecutive naturals, for example, 678 + ... + 1318.

It is an arithmetic number, because the mean of its divisors is an integer number (120375).

2⁶³⁹⁷¹⁸ is an apocalyptic number.

639718 is a deficient number, since it is larger than the sum of its proper divisors (323282).

639718 is a wasteful number, since it uses less digits than its factorization.

639718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1142.

The product of its digits is 9072, while the sum is 34.

The square root of 639718 is about 799.8237305807. The cubic root of 639718 is about 86.1647284380.

The spelling of 639718 in words is "six hundred thirty-nine thousand, seven hundred eighteen".