1211221120 has 64 divisors (see below), whose sum is σ = 3048004800. Its totient is φ = 458984448.

The previous prime is 1211221111. The next prime is 1211221129. The reversal of 1211221120 is 211221121.

It is an interprime number because it is at equal distance from previous prime (1211221111) and next prime (1211221129).

It is a tau number, because it is divible by the number of its divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 1211221120.

It is not an unprimeable number, because it can be changed into a prime (1211221129) 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, 37644 + ... + 61963.

It is an arithmetic number, because the mean of its divisors is an integer number (47625075).

Almost surely, 2^1211221120 is an apocalyptic number.

1211221120 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1211221120 is an abundant number, since it is smaller than the sum of its proper divisors (1836783680).

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

1211221120 is an equidigital number, since it uses as much as digits as its factorization.

1211221120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99645 (or 99633 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 1211221120 is about 34802.6022015596. The cubic root of 1211221120 is about 1065.9605813175.

Adding to 1211221120 its reverse (211221121), we get a palindrome (1422442241).

Subtracting from 1211221120 its reverse (211221121), we obtain a palindrome (999999999).

The spelling of 1211221120 in words is "one billion, two hundred eleven million, two hundred twenty-one thousand, one hundred twenty".