1221102220 has 48 divisors (see below), whose sum is σ = 2768562720. Its totient is φ = 449726976.

The previous prime is 1221102193. The next prime is 1221102229. The reversal of 1221102220 is 222011221.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a self number, because there is not a number n which added to its sum of digits gives 1221102220.

It is not an unprimeable number, because it can be changed into a prime (1221102229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 100599 + ... + 112081.

It is an arithmetic number, because the mean of its divisors is an integer number (57678390).

Almost surely, 2^1221102220 is an apocalyptic number.

1221102220 is a gapful number since it is divisible by the number (10) 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 1221102220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1384281360).

1221102220 is an abundant number, since it is smaller than the sum of its proper divisors (1547460500).

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

1221102220 is a wasteful number, since it uses less digits than its factorization.

1221102220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11914 (or 11912 counting only the distinct ones).

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

The square root of 1221102220 is about 34944.2730644093. The cubic root of 1221102220 is about 1068.8514242288.

Adding to 1221102220 its reverse (222011221), we get a palindrome (1443113441).

Subtracting from 1221102220 its reverse (222011221), we obtain a palindrome (999090999).

The spelling of 1221102220 in words is "one billion, two hundred twenty-one million, one hundred two thousand, two hundred twenty".