638216428 has 24 divisors (see below), whose sum is σ = 1131017888. Its totient is φ = 315086976.

The previous prime is 638216399. The next prime is 638216471. The reversal of 638216428 is 824612836.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 151600 + ... + 155752.

Almost surely, 2^638216428 is an apocalyptic number.

It is an amenable number.

638216428 is a deficient number, since it is larger than the sum of its proper divisors (492801460).

638216428 is a wasteful number, since it uses less digits than its factorization.

638216428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4633 (or 4631 counting only the distinct ones).

The product of its digits is 110592, while the sum is 40.

The square root of 638216428 is about 25262.9457506444. The cubic root of 638216428 is about 860.9725917471.

The spelling of 638216428 in words is "six hundred thirty-eight million, two hundred sixteen thousand, four hundred twenty-eight".