638009 has 4 divisors (see below), whose sum is σ = 642804. Its totient is φ = 633216.
The previous prime is 637939. The next prime is 638023. The reversal of 638009 is 900836.
It is a happy number.
It is a semiprime because it is the product of two primes.
It can be written as a sum of positive squares in 2 ways, for example, as 211600 + 426409 = 460^2 + 653^2 .
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-638009 is a prime.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (638059) 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, 2192 + ... + 2465.
It is an arithmetic number, because the mean of its divisors is an integer number (160701).
2638009 is an apocalyptic number.
It is an amenable number.
638009 is a deficient number, since it is larger than the sum of its proper divisors (4795).
638009 is a wasteful number, since it uses less digits than its factorization.
638009 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 4794.
The product of its (nonzero) digits is 1296, while the sum is 26.
The square root of 638009 is about 798.7546556985. The cubic root of 638009 is about 86.0879306164.
The spelling of 638009 in words is "six hundred thirty-eight thousand, nine".
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