638816243 has 8 divisors (see below), whose sum is σ = 689943408. Its totient is φ = 587973024.

The previous prime is 638816239. The next prime is 638816291. The reversal of 638816243 is 342618836.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 638816243 - 2² = 638816239 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 638816243.

It is not an unprimeable number, because it can be changed into a prime (638816543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 66296 + ... + 75317.

It is an arithmetic number, because the mean of its divisors is an integer number (86242926).

Almost surely, 2^638816243 is an apocalyptic number.

638816243 is a deficient number, since it is larger than the sum of its proper divisors (51127165).

638816243 is a wasteful number, since it uses less digits than its factorization.

638816243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141973.

The product of its digits is 165888, while the sum is 41.

The square root of 638816243 is about 25274.8144009011. The cubic root of 638816243 is about 861.2422299415.

The spelling of 638816243 in words is "six hundred thirty-eight million, eight hundred sixteen thousand, two hundred forty-three".