638409 has 8 divisors (see below), whose sum is σ = 855712. Its totient is φ = 423360.

The previous prime is 638371. The next prime is 638423. The reversal of 638409 is 904836.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 638409 - 2¹² = 634313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638459) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 282 + ... + 1164.

It is an arithmetic number, because the mean of its divisors is an integer number (106964).

2⁶³⁸⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

638409 is a deficient number, since it is larger than the sum of its proper divisors (217303).

638409 is a wasteful number, since it uses less digits than its factorization.

638409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1127.

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 638409 is about 799.0050062421. The cubic root of 638409 is about 86.1059178122.

The spelling of 638409 in words is "six hundred thirty-eight thousand, four hundred nine".