221428028 has 6 divisors (see below), whose sum is σ = 387499056. Its totient is φ = 110714012.

The previous prime is 221428013. The next prime is 221428127. The reversal of 221428028 is 820824122.

221428028 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27678500 + ... + 27678507.

It is an arithmetic number, because the mean of its divisors is an integer number (64583176).

Almost surely, 2^221428028 is an apocalyptic number.

It is an amenable number.

221428028 is a deficient number, since it is larger than the sum of its proper divisors (166071028).

221428028 is a wasteful number, since it uses less digits than its factorization.

221428028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55357011 (or 55357009 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 29.

The square root of 221428028 is about 14880.4579230614. The cubic root of 221428028 is about 604.9844296246.

The spelling of 221428028 in words is "two hundred twenty-one million, four hundred twenty-eight thousand, twenty-eight".