638794809 has 16 divisors (see below), whose sum is σ = 957768000. Its totient is φ = 420730848.

The previous prime is 638794789. The next prime is 638794811. The reversal of 638794809 is 908497836.

It is not a de Polignac number, because 638794809 - 2¹⁵ = 638762041 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638794909) 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, 140284 + ... + 144765.

It is an arithmetic number, because the mean of its divisors is an integer number (59860500).

Almost surely, 2^638794809 is an apocalyptic number.

It is an amenable number.

638794809 is a deficient number, since it is larger than the sum of its proper divisors (318973191).

638794809 is a wasteful number, since it uses less digits than its factorization.

638794809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285141 (or 285135 counting only the distinct ones).

The product of its (nonzero) digits is 2612736, while the sum is 54.

The square root of 638794809 is about 25274.3903784048. The cubic root of 638794809 is about 861.2325975041.

The spelling of 638794809 in words is "six hundred thirty-eight million, seven hundred ninety-four thousand, eight hundred nine".