639735639 has 16 divisors (see below), whose sum is σ = 910770432. Its totient is φ = 398458368.

The previous prime is 639735637. The next prime is 639735647. The reversal of 639735639 is 936537936.

639735639 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 639735639 - 2¹ = 639735637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 639735591 and 639735600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639735637) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 104842 + ... + 110775.

It is an arithmetic number, because the mean of its divisors is an integer number (56923152).

Almost surely, 2^639735639 is an apocalyptic number.

639735639 is a gapful number since it is divisible by the number (69) formed by its first and last digit.

639735639 is a deficient number, since it is larger than the sum of its proper divisors (271034793).

639735639 is a wasteful number, since it uses less digits than its factorization.

639735639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215686.

The product of its digits is 2755620, while the sum is 51.

The square root of 639735639 is about 25292.9958486534. The cubic root of 639735639 is about 861.6552037321.

The spelling of 639735639 in words is "six hundred thirty-nine million, seven hundred thirty-five thousand, six hundred thirty-nine".