638680225 has 24 divisors (see below), whose sum is σ = 839966328. Its totient is φ = 480076800.

The previous prime is 638680223. The next prime is 638680241. The reversal of 638680225 is 522086836.

It can be written as a sum of positive squares in 12 ways, for example, as 139783329 + 498896896 = 11823^2 + 22336^2 .

It is not a de Polignac number, because 638680225 - 2¹ = 638680223 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638680223) 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 23 ways as a sum of consecutive naturals, for example, 399127 + ... + 400723.

It is an arithmetic number, because the mean of its divisors is an integer number (34998597).

Almost surely, 2^638680225 is an apocalyptic number.

It is an amenable number.

638680225 is a deficient number, since it is larger than the sum of its proper divisors (201286103).

638680225 is a wasteful number, since it uses less digits than its factorization.

638680225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2565 (or 2560 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 40.

The square root of 638680225 is about 25272.1234762732. The cubic root of 638680225 is about 861.1810998110.

The spelling of 638680225 in words is "six hundred thirty-eight million, six hundred eighty thousand, two hundred twenty-five".