639730 has 64 divisors (see below), whose sum is σ = 1532160. Its totient is φ = 186624.

The previous prime is 639719. The next prime is 639731. The reversal of 639730 is 37936.

639730 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (639731) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17272 + ... + 17308.

It is an arithmetic number, because the mean of its divisors is an integer number (23940).

2⁶³⁹⁷³⁰ is an apocalyptic number.

639730 is an abundant number, since it is smaller than the sum of its proper divisors (892430).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639730 is a wasteful number, since it uses less digits than its factorization.

639730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83.

The product of its (nonzero) digits is 3402, while the sum is 28.

The square root of 639730 is about 799.8312321984. The cubic root of 639730 is about 86.1652672016.

It can be divided in two parts, 639 and 730, that added together give a square (1369 = 37²).

The spelling of 639730 in words is "six hundred thirty-nine thousand, seven hundred thirty".