1221120220 has 24 divisors (see below), whose sum is σ = 2626899408. Its totient is φ = 476534400.

The previous prime is 1221120211. The next prime is 1221120233. The reversal of 1221120220 is 220211221.

It is a happy number.

It is a super-2 number, since 2×1221120220² = 2982269183385696800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221120220.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 743766 + ... + 745405.

It is an arithmetic number, because the mean of its divisors is an integer number (109454142).

Almost surely, 2^1221120220 is an apocalyptic number.

1221120220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221120220 is an abundant number, since it is smaller than the sum of its proper divisors (1405779188).

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

1221120220 is a wasteful number, since it uses less digits than its factorization.

1221120220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1489221 (or 1489219 counting only the distinct ones).

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

The square root of 1221120220 is about 34944.5306163926. The cubic root of 1221120220 is about 1068.8566761045.

Adding to 1221120220 its reverse (220211221), we get a palindrome (1441331441).

The spelling of 1221120220 in words is "one billion, two hundred twenty-one million, one hundred twenty thousand, two hundred twenty".