639440109 has 48 divisors (see below), whose sum is σ = 1190062720. Its totient is φ = 332164800.

The previous prime is 639440101. The next prime is 639440167. The reversal of 639440109 is 901044936.

639440109 is a `hidden beast` number, since 639 + 4 + 4 + 0 + 10 + 9 = 666.

639440109 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 639440109 - 2³ = 639440101 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639440101) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8889 + ... + 36849.

Almost surely, 2^639440109 is an apocalyptic number.

It is an amenable number.

639440109 is a deficient number, since it is larger than the sum of its proper divisors (550622611).

639440109 is a wasteful number, since it uses less digits than its factorization.

639440109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27999 (or 27982 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 639440109 is about 25287.1530426025. The cubic root of 639440109 is about 861.5225009048.

The spelling of 639440109 in words is "six hundred thirty-nine million, four hundred forty thousand, one hundred nine".