1211311221 has 16 divisors (see below), whose sum is σ = 1643192448. Its totient is φ = 793512000.

The previous prime is 1211311219. The next prime is 1211311259. The reversal of 1211311221 is 1221131121.

It is not a de Polignac number, because 1211311221 - 2¹ = 1211311219 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1211311221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211311201) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 223696 + ... + 229046.

It is an arithmetic number, because the mean of its divisors is an integer number (102699528).

Almost surely, 2^1211311221 is an apocalyptic number.

It is an amenable number.

1211311221 is a deficient number, since it is larger than the sum of its proper divisors (431881227).

1211311221 is a wasteful number, since it uses less digits than its factorization.

1211311221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6652.

The product of its digits is 24, while the sum is 15.

The square root of 1211311221 is about 34803.8966352907. The cubic root of 1211311221 is about 1065.9870124212.

Adding to 1211311221 its reverse (1221131121), we get a palindrome (2432442342).

The spelling of 1211311221 in words is "one billion, two hundred eleven million, three hundred eleven thousand, two hundred twenty-one".