121212111905 has 4 divisors (see below), whose sum is σ = 145454534292. Its totient is φ = 96969689520.

The previous prime is 121212111899. The next prime is 121212111931. The reversal of 121212111905 is 509111212121.

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 79682562961 + 41529548944 = 282281^2 + 203788^2 .

It is not a de Polignac number, because 121212111905 - 2²⁰ = 121211063329 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12121211186 + ... + 12121211195.

It is an arithmetic number, because the mean of its divisors is an integer number (36363633573).

Almost surely, 2^121212111905 is an apocalyptic number.

It is an amenable number.

121212111905 is a deficient number, since it is larger than the sum of its proper divisors (24242422387).

121212111905 is an equidigital number, since it uses as much as digits as its factorization.

121212111905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24242422386.

The product of its (nonzero) digits is 360, while the sum is 26.

The spelling of 121212111905 in words is "one hundred twenty-one billion, two hundred twelve million, one hundred eleven thousand, nine hundred five".