638910243 has 12 divisors (see below), whose sum is σ = 923794560. Its totient is φ = 425513616.

The previous prime is 638910199. The next prime is 638910247. The reversal of 638910243 is 342019836.

638910243 is a `hidden beast` number, since 638 + 9 + 10 + 2 + 4 + 3 = 666.

It is not a de Polignac number, because 638910243 - 2⁸ = 638909987 is a prime.

It is a super-2 number, since 2×638910243² = 816412597220638098, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 638910198 and 638910207.

It is not an unprimeable number, because it can be changed into a prime (638910247) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 25923 + ... + 44156.

It is an arithmetic number, because the mean of its divisors is an integer number (76982880).

Almost surely, 2^638910243 is an apocalyptic number.

638910243 is a deficient number, since it is larger than the sum of its proper divisors (284884317).

638910243 is a wasteful number, since it uses less digits than its factorization.

638910243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71098 (or 71095 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 638910243 is about 25276.6738911590. The cubic root of 638910243 is about 861.2844709876.

The spelling of 638910243 in words is "six hundred thirty-eight million, nine hundred ten thousand, two hundred forty-three".