20121221101 has 4 divisors (see below), whose sum is σ = 20129760252.
Its totient is φ = 20112681952.
The previous prime is 20121221041. The next prime is 20121221117. The reversal of 20121221101 is 10112212102.
It is a semiprime because it is the product of two primes.
It can be written as a sum of positive squares in 2 ways, for example, as 11425472100 + 8695749001 = 106890^2 + 93251^2
It is a cyclic number.
It is not a de Polignac number, because 20121221101 - 215 = 20121188333 is a prime.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (20121221161) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4266040 + ... + 4270753.
It is an arithmetic number, because the mean of its divisors is an integer number (5032440063).
Almost surely, 220121221101 is an apocalyptic number.
It is an amenable number.
20121221101 is a deficient number, since it is larger than the sum of its proper divisors (8539151).
20121221101 is an equidigital number, since it uses as much as digits as its factorization.
20121221101 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 8539150.
The product of its (nonzero) digits is 16, while the sum is 13.
Adding to 20121221101 its reverse (10112212102), we get a palindrome (30233433203).
The spelling of 20121221101 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-one thousand, one hundred one".