1221331121 has 4 divisors (see below), whose sum is σ = 1221445632. Its totient is φ = 1221216612.

The previous prime is 1221331117. The next prime is 1221331219. The reversal of 1221331121 is 1211331221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1221331121 - 2² = 1221331117 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221331121.

It is not an unprimeable number, because it can be changed into a prime (1221333121) 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 3 ways as a sum of consecutive naturals, for example, 39401 + ... + 63206.

It is an arithmetic number, because the mean of its divisors is an integer number (305361408).

Almost surely, 2^1221331121 is an apocalyptic number.

It is an amenable number.

1221331121 is a deficient number, since it is larger than the sum of its proper divisors (114511).

1221331121 is a wasteful number, since it uses less digits than its factorization.

1221331121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114510.

The product of its digits is 72, while the sum is 17.

The square root of 1221331121 is about 34947.5481400341. The cubic root of 1221331121 is about 1068.9182070282.

Adding to 1221331121 its reverse (1211331221), we get a palindrome (2432662342).

It can be divided in two parts, 12213 and 31121, that added together give a palindrome (43334).

The spelling of 1221331121 in words is "one billion, two hundred twenty-one million, three hundred thirty-one thousand, one hundred twenty-one".