221440 has 36 divisors (see below), whose sum is σ = 533484. Its totient is φ = 88064.

The previous prime is 221413. The next prime is 221447. The reversal of 221440 is 44122.

221440 is digitally balanced in base 3, 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 147456 + 73984 = 384^2 + 272^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 221440.

It is not an unprimeable number, because it can be changed into a prime (221447) by changing a digit.

221440 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 (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1194 + ... + 1366.

It is an arithmetic number, because the mean of its divisors is an integer number (14819).

2²²¹⁴⁴⁰ is an apocalyptic number.

221440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (266742).

221440 is an abundant number, since it is smaller than the sum of its proper divisors (312044).

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

221440 is an equidigital number, since it uses as much as digits as its factorization.

221440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194 (or 180 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 13.

The square root of 221440 is about 470.5741174353. The cubic root of 221440 is about 60.4995332705.

Adding to 221440 its reverse (44122), we get a palindrome (265562).

The spelling of 221440 in words is "two hundred twenty-one thousand, four hundred forty", and thus it is an iban number.