639958 has 16 divisors (see below), whose sum is σ = 1103040. Its totient is φ = 275400.

The previous prime is 639949. The next prime is 639959. The reversal of 639958 is 859936.

It is a self number, because there is not a number n which added to its sum of digits gives 639958.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639959) 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, 348 + ... + 1183.

It is an arithmetic number, because the mean of its divisors is an integer number (68940).

2⁶³⁹⁹⁵⁸ is an apocalyptic number.

639958 is a deficient number, since it is larger than the sum of its proper divisors (463082).

639958 is a wasteful number, since it uses less digits than its factorization.

639958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1563.

The product of its digits is 58320, while the sum is 40.

The square root of 639958 is about 799.9737495693. The cubic root of 639958 is about 86.1755024297.

The spelling of 639958 in words is "six hundred thirty-nine thousand, nine hundred fifty-eight".