221131220 has 12 divisors (see below), whose sum is σ = 464375604. Its totient is φ = 88452480.

The previous prime is 221131219. The next prime is 221131231. The reversal of 221131220 is 22131122.

It is a happy number.

221131220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 145057936 + 76073284 = 12044^2 + 8722^2 .

It is a junction number, because it is equal to n+sod(n) for n = 221131195 and 221131204.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5528261 + ... + 5528300.

It is an arithmetic number, because the mean of its divisors is an integer number (38697967).

Almost surely, 2^221131220 is an apocalyptic number.

221131220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221131220 is an abundant number, since it is smaller than the sum of its proper divisors (243244384).

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

221131220 is a wasteful number, since it uses less digits than its factorization.

221131220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11056570 (or 11056568 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 221131220 is about 14870.4814985931. The cubic root of 221131220 is about 604.7139963663.

Adding to 221131220 its reverse (22131122), we get a palindrome (243262342).

The spelling of 221131220 in words is "two hundred twenty-one million, one hundred thirty-one thousand, two hundred twenty".