20121221135 has 4 divisors (see below), whose sum is σ = 24145465368. Its totient is φ = 16096976904.

The previous prime is 20121221129. The next prime is 20121221137. The reversal of 20121221135 is 53112212102.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20121221135 - 2⁸ = 20121220879 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 (20121221137) 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, 2012122109 + ... + 2012122118.

It is an arithmetic number, because the mean of its divisors is an integer number (6036366342).

Almost surely, 2^20121221135 is an apocalyptic number.

20121221135 is a deficient number, since it is larger than the sum of its proper divisors (4024244233).

20121221135 is an equidigital number, since it uses as much as digits as its factorization.

20121221135 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4024244232.

The product of its (nonzero) digits is 240, while the sum is 20.

Adding to 20121221135 its reverse (53112212102), we get a palindrome (73233433237).

The spelling of 20121221135 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-one thousand, one hundred thirty-five".