638399 has 4 divisors (see below), whose sum is σ = 646560. Its totient is φ = 630240.

The previous prime is 638371. The next prime is 638423. The reversal of 638399 is 993836.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638399 is a prime.

It is a Duffinian number.

It is a plaindrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638359) 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, 3962 + ... + 4119.

It is an arithmetic number, because the mean of its divisors is an integer number (161640).

2⁶³⁸³⁹⁹ is an apocalyptic number.

638399 is a deficient number, since it is larger than the sum of its proper divisors (8161).

638399 is an equidigital number, since it uses as much as digits as its factorization.

638399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8160.

The product of its digits is 34992, while the sum is 38.

The square root of 638399 is about 798.9987484346. The cubic root of 638399 is about 86.1054682239.

The spelling of 638399 in words is "six hundred thirty-eight thousand, three hundred ninety-nine".