1221221121 has 16 divisors (see below), whose sum is σ = 1674210048. Its totient is φ = 791337600.

The previous prime is 1221221119. The next prime is 1221221153. The reversal of 1221221121 is 1211221221.

It is not a de Polignac number, because 1221221121 - 2¹ = 1221221119 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221221121.

It is not an unprimeable number, because it can be changed into a prime (1221221621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15015 + ... + 51651.

It is an arithmetic number, because the mean of its divisors is an integer number (104638128).

Almost surely, 2^1221221121 is an apocalyptic number.

It is an amenable number.

1221221121 is a deficient number, since it is larger than the sum of its proper divisors (452988927).

1221221121 is a wasteful number, since it uses less digits than its factorization.

1221221121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36952.

The product of its digits is 32, while the sum is 15.

The square root of 1221221121 is about 34945.9743175090. The cubic root of 1221221121 is about 1068.8861151216.

Adding to 1221221121 its reverse (1211221221), we get a palindrome (2432442342).

It can be divided in two parts, 1221221 and 121, that multiplied together give a palindrome (147767741).

The spelling of 1221221121 in words is "one billion, two hundred twenty-one million, two hundred twenty-one thousand, one hundred twenty-one".