221028 has 24 divisors (see below), whose sum is σ = 523488. Its totient is φ = 72576.

The previous prime is 221021. The next prime is 221047. The reversal of 221028 is 820122.

It is a junction number, because it is equal to n+sod(n) for n = 220998 and 221016.

It is not an unprimeable number, because it can be changed into a prime (221021) by changing a digit.

221028 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 7 ways as a sum of consecutive naturals, for example, 1275 + ... + 1437.

It is an arithmetic number, because the mean of its divisors is an integer number (21812).

2²²¹⁰²⁸ is an apocalyptic number.

It is an amenable number.

221028 is an abundant number, since it is smaller than the sum of its proper divisors (302460).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221028 is a wasteful number, since it uses less digits than its factorization.

221028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283 (or 281 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 221028 is about 470.1361504926. The cubic root of 221028 is about 60.4619891920.

The spelling of 221028 in words is "two hundred twenty-one thousand, twenty-eight".