638755109 has 4 divisors (see below), whose sum is σ = 642674016. Its totient is φ = 634836204.

The previous prime is 638755079. The next prime is 638755111. The reversal of 638755109 is 901557836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638755109 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 638755109.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638755199) 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 3 ways as a sum of consecutive naturals, for example, 1959209 + ... + 1959534.

It is an arithmetic number, because the mean of its divisors is an integer number (160668504).

Almost surely, 2^638755109 is an apocalyptic number.

It is an amenable number.

638755109 is a deficient number, since it is larger than the sum of its proper divisors (3918907).

638755109 is a wasteful number, since it uses less digits than its factorization.

638755109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3918906.

The product of its (nonzero) digits is 226800, while the sum is 44.

The square root of 638755109 is about 25273.6049862302. The cubic root of 638755109 is about 861.2147557590.

The spelling of 638755109 in words is "six hundred thirty-eight million, seven hundred fifty-five thousand, one hundred nine".