221628 has 48 divisors (see below), whose sum is σ = 596736. Its totient is φ = 63360.

The previous prime is 221623. The next prime is 221653. The reversal of 221628 is 826122.

It is a nialpdrome in base 12.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221628.

It is not an unprimeable number, because it can be changed into a prime (221621) by changing a digit.

221628 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 15 ways as a sum of consecutive naturals, for example, 3000 + ... + 3072.

It is an arithmetic number, because the mean of its divisors is an integer number (12432).

2²²¹⁶²⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221628, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (298368).

221628 is an abundant number, since it is smaller than the sum of its proper divisors (375108).

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

221628 is a wasteful number, since it uses less digits than its factorization.

221628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114 (or 112 counting only the distinct ones).

The product of its digits is 384, while the sum is 21.

The square root of 221628 is about 470.7738310484. The cubic root of 221628 is about 60.5166495624.

The spelling of 221628 in words is "two hundred twenty-one thousand, six hundred twenty-eight".