1211221205 has 8 divisors (see below), whose sum is σ = 1487267232. Its totient is φ = 946442448.

The previous prime is 1211221199. The next prime is 1211221213. The reversal of 1211221205 is 5021221121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211221205 is a prime.

It is a Duffinian number.

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, 2816579 + ... + 2817008.

It is an arithmetic number, because the mean of its divisors is an integer number (185908404).

Almost surely, 2^1211221205 is an apocalyptic number.

It is an amenable number.

1211221205 is a deficient number, since it is larger than the sum of its proper divisors (276046027).

1211221205 is an equidigital number, since it uses as much as digits as its factorization.

1211221205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5633635.

The product of its (nonzero) digits is 80, while the sum is 17.

The square root of 1211221205 is about 34802.6034227326. The cubic root of 1211221205 is about 1065.9606062528.

Adding to 1211221205 its reverse (5021221121), we get a palindrome (6232442326).

The spelling of 1211221205 in words is "one billion, two hundred eleven million, two hundred twenty-one thousand, two hundred five".