221620224 has 96 divisors (see below), whose sum is σ = 675380160. Its totient is φ = 63307776.

The previous prime is 221620213. The next prime is 221620229. The reversal of 221620224 is 422026122.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 221620224.

It is not an unprimeable number, because it can be changed into a prime (221620229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40432 + ... + 45584.

It is an arithmetic number, because the mean of its divisors is an integer number (7035210).

Almost surely, 2^221620224 is an apocalyptic number.

221620224 is a gapful number since it is divisible by the number (24) 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 221620224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (337690080).

221620224 is an abundant number, since it is smaller than the sum of its proper divisors (453759936).

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

221620224 is an equidigital number, since it uses as much as digits as its factorization.

221620224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5185 (or 5165 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 21.

The square root of 221620224 is about 14886.9145224926. The cubic root of 221620224 is about 605.1594179536.

Adding to 221620224 its reverse (422026122), we get a palindrome (643646346).

The spelling of 221620224 in words is "two hundred twenty-one million, six hundred twenty thousand, two hundred twenty-four".