221021220 has 96 divisors (see below), whose sum is σ = 713680128. Its totient is φ = 50061312.

The previous prime is 221021197. The next prime is 221021221. The reversal of 221021220 is 22120122.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 221021196 and 221021205.

It is not an unprimeable number, because it can be changed into a prime (221021221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45132 + ... + 49788.

It is an arithmetic number, because the mean of its divisors is an integer number (7434168).

Almost surely, 2^221021220 is an apocalyptic number.

221021220 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 221021220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (356840064).

221021220 is an abundant number, since it is smaller than the sum of its proper divisors (492658908).

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

221021220 is a wasteful number, since it uses less digits than its factorization.

221021220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4789 (or 4787 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

The square root of 221021220 is about 14866.7824360216. The cubic root of 221021220 is about 604.6137096491.

Adding to 221021220 its reverse (22120122), we get a palindrome (243141342).

The spelling of 221021220 in words is "two hundred twenty-one million, twenty-one thousand, two hundred twenty".