638820000 has 720 divisors, whose sum is σ = 2881327680. Its totient is φ = 134784000.

The previous prime is 638819947. The next prime is 638820001. The reversal of 638820000 is 28836.

638820000 is a `hidden beast` number, since 638 + 8 + 20 + 0 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (638820001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 49139994 + ... + 49140006.

It is an arithmetic number, because the mean of its divisors is an integer number (4001844).

Almost surely, 2^638820000 is an apocalyptic number.

638820000 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638820000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1440663840).

638820000 is an abundant number, since it is smaller than the sum of its proper divisors (2242507680).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638820000 is a wasteful number, since it uses less digits than its factorization.

638820000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72 (or 30 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 638820000 is about 25274.8887237907. Note that the first 3 decimals coincide. The cubic root of 638820000 is about 861.2439183147.

Adding to 638820000 its reverse (28836), we get a palindrome (638848836).

The spelling of 638820000 in words is "six hundred thirty-eight million, eight hundred twenty thousand".