639847 has 8 divisors (see below), whose sum is σ = 698544. Its totient is φ = 582528.

The previous prime is 639839. The next prime is 639851. The reversal of 639847 is 748936.

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 639847 - 2³ = 639839 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639857) 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 7 ways as a sum of consecutive naturals, for example, 783 + ... + 1375.

It is an arithmetic number, because the mean of its divisors is an integer number (87318).

2⁶³⁹⁸⁴⁷ is an apocalyptic number.

639847 is a deficient number, since it is larger than the sum of its proper divisors (58697).

639847 is a wasteful number, since it uses less digits than its factorization.

With its successor (639848) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (689).

639847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 689.

The product of its digits is 36288, while the sum is 37.

The square root of 639847 is about 799.9043692842. The cubic root of 639847 is about 86.1705197934.

The spelling of 639847 in words is "six hundred thirty-nine thousand, eight hundred forty-seven".