221243220 has 144 divisors (see below), whose sum is σ = 770777280. Its totient is φ = 50803200.

The previous prime is 221243207. The next prime is 221243251. The reversal of 221243220 is 22342122.

221243220 is a `hidden beast` number, since 2 + 212 + 432 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 221243193 and 221243202.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 34680 + ... + 40560.

It is an arithmetic number, because the mean of its divisors is an integer number (5352620).

Almost surely, 2^221243220 is an apocalyptic number.

221243220 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 221243220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (385388640).

221243220 is an abundant number, since it is smaller than the sum of its proper divisors (549534060).

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

221243220 is a wasteful number, since it uses less digits than its factorization.

221243220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5926 (or 5921 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 221243220 is about 14874.2468716907. The cubic root of 221243220 is about 604.8160723137.

Adding to 221243220 its reverse (22342122), we get a palindrome (243585342).

The spelling of 221243220 in words is "two hundred twenty-one million, two hundred forty-three thousand, two hundred twenty".