638320799 has 4 divisors (see below), whose sum is σ = 640215264. Its totient is φ = 636426336.

The previous prime is 638320757. The next prime is 638320807. The reversal of 638320799 is 997023836.

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

It is a cyclic number.

It is not a de Polignac number, because 638320799 - 2¹⁶ = 638255263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638320729) 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, 946727 + ... + 947400.

It is an arithmetic number, because the mean of its divisors is an integer number (160053816).

Almost surely, 2^638320799 is an apocalyptic number.

638320799 is a deficient number, since it is larger than the sum of its proper divisors (1894465).

638320799 is a wasteful number, since it uses less digits than its factorization.

638320799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1894464.

The product of its (nonzero) digits is 489888, while the sum is 47.

The square root of 638320799 is about 25265.0113595858. The cubic root of 638320799 is about 861.0195223642.

The spelling of 638320799 in words is "six hundred thirty-eight million, three hundred twenty thousand, seven hundred ninety-nine".