639707 has 4 divisors (see below), whose sum is σ = 650256. Its totient is φ = 629160.

The previous prime is 639703. The next prime is 639713. The reversal of 639707 is 707936.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 639707 - 2² = 639703 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (639701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5183 + ... + 5304.

It is an arithmetic number, because the mean of its divisors is an integer number (162564).

2⁶³⁹⁷⁰⁷ is an apocalyptic number.

639707 is a deficient number, since it is larger than the sum of its proper divisors (10549).

639707 is a wasteful number, since it uses less digits than its factorization.

639707 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10548.

The product of its (nonzero) digits is 7938, while the sum is 32.

The square root of 639707 is about 799.8168540360. The cubic root of 639707 is about 86.1642345654.

The spelling of 639707 in words is "six hundred thirty-nine thousand, seven hundred seven".