221616 has 70 divisors (see below), whose sum is σ = 677660. Its totient is φ = 69984.
The previous prime is 221603. The next prime is 221621. The reversal of 221616 is 616122.
It is a happy number.
It is a super-2 number, since 2×2216162 = 98227302912, which contains 22 as substring.
It is a Harshad number since it is a multiple of its sum of digits (18).
It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.
Its product of digits (144) is a multiple of the sum of its prime divisors (24).
It is a nialpdrome in base 6 and base 12.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221616.
It is an unprimeable number.
221616 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 13 ways as a sum of consecutive naturals, for example, 11655 + ... + 11673.
2221616 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 221616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (338830).
221616 is an abundant number, since it is smaller than the sum of its proper divisors (456044).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
221616 is an equidigital number, since it uses as much as digits as its factorization.
221616 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 45 (or 24 counting only the distinct ones).
The product of its digits is 144, while the sum is 18.
The square root of 221616 is about 470.7610859024. The cubic root of 221616 is about 60.5155573224.
Adding to 221616 its reverse (616122), we get a palindrome (837738).
The spelling of 221616 in words is "two hundred twenty-one thousand, six hundred sixteen".
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