639807 has 8 divisors (see below), whose sum is σ = 974976. Its totient is φ = 365592.

The previous prime is 639757. The next prime is 639833. The reversal of 639807 is 708936.

It is a happy number.

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

It is not a de Polignac number, because 639807 - 2⁷ = 639679 is a prime.

639807 is a lucky number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639807.

It is not an unprimeable number, because it can be changed into a prime (639857) 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, 15213 + ... + 15254.

It is an arithmetic number, because the mean of its divisors is an integer number (121872).

2⁶³⁹⁸⁰⁷ is an apocalyptic number.

639807 is a deficient number, since it is larger than the sum of its proper divisors (335169).

639807 is a wasteful number, since it uses less digits than its factorization.

639807 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30477.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 639807 is about 799.8793659046. The cubic root of 639807 is about 86.1687241075.

It can be divided in two parts, 63 and 9807, that added together give a triangular number (9870 = T₁₄₀).

The spelling of 639807 in words is "six hundred thirty-nine thousand, eight hundred seven".