221121220 has 24 divisors (see below), whose sum is σ = 465583104. Its totient is φ = 88214496.

The previous prime is 221121217. The next prime is 221121223. The reversal of 221121220 is 22121122.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (221121217) and next prime (221121223).

It is a self number, because there is not a number n which added to its sum of digits gives 221121220.

It is not an unprimeable number, because it can be changed into a prime (221121223) 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, 6774 + ... + 22093.

It is an arithmetic number, because the mean of its divisors is an integer number (19399296).

Almost surely, 2^221121220 is an apocalyptic number.

221121220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221121220 is an abundant number, since it is smaller than the sum of its proper divisors (244461884).

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

221121220 is a wasteful number, since it uses less digits than its factorization.

221121220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29259 (or 29257 counting only the distinct ones).

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

The square root of 221121220 is about 14870.1452582011. The cubic root of 221121220 is about 604.7048807665.

Adding to 221121220 its reverse (22121122), we get a palindrome (243242342).

It can be divided in two parts, 22112 and 1220, that added together give a palindrome (23332).

The spelling of 221121220 in words is "two hundred twenty-one million, one hundred twenty-one thousand, two hundred twenty".