638603666 has 8 divisors (see below), whose sum is σ = 972202800. Its totient is φ = 314536068.

The previous prime is 638603663. The next prime is 638603677. The reversal of 638603666 is 666306836.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (638603663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2382716 + ... + 2382983.

It is an arithmetic number, because the mean of its divisors is an integer number (121525350).

Almost surely, 2^638603666 is an apocalyptic number.

638603666 is a deficient number, since it is larger than the sum of its proper divisors (333599134).

638603666 is a wasteful number, since it uses less digits than its factorization.

638603666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4765768.

The product of its (nonzero) digits is 559872, while the sum is 44.

The square root of 638603666 is about 25270.6087382160. The cubic root of 638603666 is about 861.1466883295.

The spelling of 638603666 in words is "six hundred thirty-eight million, six hundred three thousand, six hundred sixty-six".