638817843 has 16 divisors (see below), whose sum is σ = 891104256. Its totient is φ = 406647360.

The previous prime is 638817833. The next prime is 638817863. The reversal of 638817843 is 348718836.

It is not a de Polignac number, because 638817843 - 2⁸ = 638817587 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 638817792 and 638817801.

It is not an unprimeable number, because it can be changed into a prime (638817833) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49471 + ... + 61032.

It is an arithmetic number, because the mean of its divisors is an integer number (55694016).

Almost surely, 2^638817843 is an apocalyptic number.

638817843 is a deficient number, since it is larger than the sum of its proper divisors (252286413).

638817843 is a wasteful number, since it uses less digits than its factorization.

638817843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110594.

The product of its digits is 774144, while the sum is 48.

The square root of 638817843 is about 25274.8460529436. The cubic root of 638817843 is about 861.2429489727.

The spelling of 638817843 in words is "six hundred thirty-eight million, eight hundred seventeen thousand, eight hundred forty-three".