638891855 has 8 divisors (see below), whose sum is σ = 876194592. Its totient is φ = 438097248.

The previous prime is 638891849. The next prime is 638891879. The reversal of 638891855 is 558198836.

638891855 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

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 638891855 - 2¹² = 638887759 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 638891797 and 638891806.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9126992 + ... + 9127061.

It is an arithmetic number, because the mean of its divisors is an integer number (109524324).

Almost surely, 2^638891855 is an apocalyptic number.

638891855 is a deficient number, since it is larger than the sum of its proper divisors (237302737).

638891855 is a wasteful number, since it uses less digits than its factorization.

638891855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18254065.

The product of its digits is 2073600, while the sum is 53.

The square root of 638891855 is about 25276.3101539762. The cubic root of 638891855 is about 861.2762082459.

The spelling of 638891855 in words is "six hundred thirty-eight million, eight hundred ninety-one thousand, eight hundred fifty-five".