638666625 has 32 divisors (see below), whose sum is σ = 1125266688. Its totient is φ = 320582400.

The previous prime is 638666603. The next prime is 638666647. The reversal of 638666625 is 526666836.

It is an interprime number because it is at equal distance from previous prime (638666603) and next prime (638666647).

It is not a de Polignac number, because 638666625 - 2¹¹ = 638664577 is a prime.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 43717 + ... + 56466.

It is an arithmetic number, because the mean of its divisors is an integer number (35164584).

Almost surely, 2^638666625 is an apocalyptic number.

It is an amenable number.

638666625 is a deficient number, since it is larger than the sum of its proper divisors (486600063).

638666625 is a wasteful number, since it uses less digits than its factorization.

638666625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100218 (or 100208 counting only the distinct ones).

The product of its digits is 1866240, while the sum is 48.

The square root of 638666625 is about 25271.8544036642. The cubic root of 638666625 is about 861.1749871297.

The spelling of 638666625 in words is "six hundred thirty-eight million, six hundred sixty-six thousand, six hundred twenty-five".