20121221105 has 8 divisors (see below), whose sum is σ = 24155586600. Its totient is φ = 16090229376.

The previous prime is 20121221041. The next prime is 20121221117. The reversal of 20121221105 is 50112212102.

It can be written as a sum of positive squares in 4 ways, for example, as 187169761 + 19934051344 = 13681^2 + 141188^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20121221105 - 2⁶ = 20121221041 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 830300 + ... + 854189.

It is an arithmetic number, because the mean of its divisors is an integer number (3019448325).

Almost surely, 2^20121221105 is an apocalyptic number.

It is an amenable number.

20121221105 is a deficient number, since it is larger than the sum of its proper divisors (4034365495).

20121221105 is a wasteful number, since it uses less digits than its factorization.

20121221105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1686883.

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

Adding to 20121221105 its reverse (50112212102), we get a palindrome (70233433207).

The spelling of 20121221105 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-one thousand, one hundred five".