221638828 has 12 divisors (see below), whose sum is σ = 387976960. Its totient is φ = 110788272.

The previous prime is 221638817. The next prime is 221638853. The reversal of 221638828 is 828836122.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16978 + ... + 27046.

Almost surely, 2^221638828 is an apocalyptic number.

It is an amenable number.

221638828 is a deficient number, since it is larger than the sum of its proper divisors (166338132).

221638828 is a wasteful number, since it uses less digits than its factorization.

221638828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15576 (or 15574 counting only the distinct ones).

The product of its digits is 73728, while the sum is 40.

The square root of 221638828 is about 14887.5393534325. The cubic root of 221638828 is about 605.1763509311.

The spelling of 221638828 in words is "two hundred twenty-one million, six hundred thirty-eight thousand, eight hundred twenty-eight".