221428 has 12 divisors (see below), whose sum is σ = 390852. Its totient is φ = 109760.

The previous prime is 221413. The next prime is 221447. The reversal of 221428 is 824122.

221428 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 191844 + 29584 = 438^2 + 172^2 .

It is a congruent number.

It is an unprimeable number.

221428 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 648 + ... + 928.

It is an arithmetic number, because the mean of its divisors is an integer number (32571).

2²²¹⁴²⁸ is an apocalyptic number.

It is an amenable number.

221428 is a deficient number, since it is larger than the sum of its proper divisors (169424).

221428 is a wasteful number, since it uses less digits than its factorization.

221428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482 (or 480 counting only the distinct ones).

The product of its digits is 256, while the sum is 19.

The square root of 221428 is about 470.5613668800. The cubic root of 221428 is about 60.4984404124.

The spelling of 221428 in words is "two hundred twenty-one thousand, four hundred twenty-eight".