221021121220 has 24 divisors (see below), whose sum is σ = 468929352024. Its totient is φ = 87497020416.

The previous prime is 221021121187. The next prime is 221021121221. The reversal of 221021121220 is 22121120122.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 194435136 + 220826686084 = 13944^2 + 469922^2 .

It is a junction number, because it is equal to n+sod(n) for n = 221021121194 and 221021121203.

It is not an unprimeable number, because it can be changed into a prime (221021121221) 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, 56962267 + ... + 56966146.

It is an arithmetic number, because the mean of its divisors is an integer number (19538723001).

Almost surely, 2^221021121220 is an apocalyptic number.

221021121220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221021121220 is an abundant number, since it is smaller than the sum of its proper divisors (247908230804).

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

221021121220 is a wasteful number, since it uses less digits than its factorization.

221021121220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113928519 (or 113928517 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 221021121220 its reverse (22121120122), we get a palindrome (243142241342).

The spelling of 221021121220 in words is "two hundred twenty-one billion, twenty-one million, one hundred twenty-one thousand, two hundred twenty".