1221221120 has 108 divisors (see below), whose sum is σ = 3402965664. Its totient is φ = 418682880.

The previous prime is 1221221119. The next prime is 1221221153. The reversal of 1221221120 is 211221221.

It is a Harshad number since it is a multiple of its sum of digits (14).

It is a junction number, because it is equal to n+sod(n) for n = 1221221095 and 1221221104.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 52985 + ... + 72455.

Almost surely, 2^1221221120 is an apocalyptic number.

1221221120 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 1221221120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1701482832).

1221221120 is an abundant number, since it is smaller than the sum of its proper divisors (2181744544).

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

1221221120 is an equidigital number, since it uses as much as digits as its factorization.

1221221120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19506 (or 19485 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 1221221120 is about 34945.9743032012. The cubic root of 1221221120 is about 1068.8861148299.

Adding to 1221221120 its reverse (211221221), we get a palindrome (1432442341).

The spelling of 1221221120 in words is "one billion, two hundred twenty-one million, two hundred twenty-one thousand, one hundred twenty".