638949835 has 16 divisors (see below), whose sum is σ = 792253440. Its totient is φ = 494183520.

The previous prime is 638949833. The next prime is 638949851. The reversal of 638949835 is 538949836.

638949835 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 638949835 - 2¹ = 638949833 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638949833) 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, 305704 + ... + 307786.

It is an arithmetic number, because the mean of its divisors is an integer number (49515840).

Almost surely, 2^638949835 is an apocalyptic number.

638949835 is a deficient number, since it is larger than the sum of its proper divisors (153303605).

638949835 is a wasteful number, since it uses less digits than its factorization.

638949835 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4098.

The product of its digits is 5598720, while the sum is 55.

The square root of 638949835 is about 25277.4570516894. The cubic root of 638949835 is about 861.3022613167.

Subtracting from 638949835 its reverse (538949836), we obtain a palindrome (99999999).

The spelling of 638949835 in words is "six hundred thirty-eight million, nine hundred forty-nine thousand, eight hundred thirty-five".