638512409 has 4 divisors (see below), whose sum is σ = 642741120. Its totient is φ = 634283700.

The previous prime is 638512403. The next prime is 638512411. The reversal of 638512409 is 904215836.

It is a happy number.

638512409 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 638512409 - 2²⁰ = 637463833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638512403) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2114129 + ... + 2114430.

It is an arithmetic number, because the mean of its divisors is an integer number (160685280).

Almost surely, 2^638512409 is an apocalyptic number.

It is an amenable number.

638512409 is a deficient number, since it is larger than the sum of its proper divisors (4228711).

638512409 is a wasteful number, since it uses less digits than its factorization.

638512409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4228710.

The product of its (nonzero) digits is 51840, while the sum is 38.

The square root of 638512409 is about 25268.8030781040. The cubic root of 638512409 is about 861.1056668471.

The spelling of 638512409 in words is "six hundred thirty-eight million, five hundred twelve thousand, four hundred nine".