638819973 has 32 divisors (see below), whose sum is σ = 1038487680. Its totient is φ = 384894720.

The previous prime is 638819947. The next prime is 638820001. The reversal of 638819973 is 379918836.

638819973 is a `hidden beast` number, since 6 + 388 + 199 + 73 = 666.

It is not a de Polignac number, because 638819973 - 2⁸ = 638819717 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638819933) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45165 + ... + 57597.

It is an arithmetic number, because the mean of its divisors is an integer number (32452740).

Almost surely, 2^638819973 is an apocalyptic number.

It is an amenable number.

638819973 is a deficient number, since it is larger than the sum of its proper divisors (399667707).

638819973 is a wasteful number, since it uses less digits than its factorization.

638819973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12626 (or 12620 counting only the distinct ones).

The product of its digits is 1959552, while the sum is 54.

The square root of 638819973 is about 25274.8881896637. Note that the first 3 decimals coincide. The cubic root of 638819973 is about 861.2439061811.

The spelling of 638819973 in words is "six hundred thirty-eight million, eight hundred nineteen thousand, nine hundred seventy-three".