221211220 has 24 divisors (see below), whose sum is σ = 471479904. Its totient is φ = 87163296.

The previous prime is 221211209. The next prime is 221211223. The reversal of 221211220 is 22112122.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 221211220.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221211223) 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, 81202 + ... + 83881.

It is an arithmetic number, because the mean of its divisors is an integer number (19644996).

Almost surely, 2^221211220 is an apocalyptic number.

221211220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221211220 is an abundant number, since it is smaller than the sum of its proper divisors (250268684).

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

221211220 is a wasteful number, since it uses less digits than its factorization.

221211220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165159 (or 165157 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 221211220 is about 14873.1711480773. The cubic root of 221211220 is about 604.7869112732.

Adding to 221211220 its reverse (22112122), we get a palindrome (243323342).

The spelling of 221211220 in words is "two hundred twenty-one million, two hundred eleven thousand, two hundred twenty".