221465 has 4 divisors (see below), whose sum is σ = 265764.
Its totient is φ = 177168.
The previous prime is 221461. The next prime is 221471. The reversal of 221465 is 564122.
Subtracting from 221465 its sum of digits (20), we obtain a triangular number (221445 = T665).
Adding to 221465 its reverse (564122), we get a palindrome (785587).
It can be divided in two parts, 221 and 465, that added together give a palindrome (686).
It is a happy number.
It is a semiprime because it is the product of two primes.
It can be written as a sum of positive squares in 2 ways, for example, as 141376 + 80089 = 376^2 + 283^2
It is a cyclic number.
It is not a de Polignac number, because 221465 - 22 = 221461 is a prime.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (221461) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22142 + ... + 22151.
It is an arithmetic number, because the mean of its divisors is an integer number (66441).
2221465 is an apocalyptic number.
It is an amenable number.
221465 is a deficient number, since it is larger than the sum of its proper divisors (44299).
221465 is an equidigital number, since it uses as much as digits as its factorization.
221465 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 44298.
The product of its digits is 480, while the sum is 20.
The square root of 221465 is about 470.6006799825.
The cubic root of 221465 is about 60.5018099315.
The spelling of 221465 in words is "two hundred twenty-one thousand, four hundred sixty-five".