638656272 has 320 divisors, whose sum is σ = 2142720000. Its totient is φ = 180652032.

The previous prime is 638656267. The next prime is 638656279. The reversal of 638656272 is 272656836.

It is a happy number.

638656272 is a `hidden beast` number, since 6 + 3 + 86 + 562 + 7 + 2 = 666.

It is not an unprimeable number, because it can be changed into a prime (638656279) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3209229 + ... + 3209427.

It is an arithmetic number, because the mean of its divisors is an integer number (6696000).

Almost surely, 2^638656272 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638656272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1071360000).

638656272 is an abundant number, since it is smaller than the sum of its proper divisors (1504063728).

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

638656272 is a wasteful number, since it uses less digits than its factorization.

638656272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 275 (or 263 counting only the distinct ones).

The product of its digits is 725760, while the sum is 45.

The square root of 638656272 is about 25271.6495702200. The cubic root of 638656272 is about 861.1703337928.

The spelling of 638656272 in words is "six hundred thirty-eight million, six hundred fifty-six thousand, two hundred seventy-two".