121212220100021 has 4 divisors (see below), whose sum is σ = 121213292916012. Its totient is φ = 121211147284032.

The previous prime is 121212220099991. The next prime is 121212220100053. The reversal of 121212220100021 is 120001022212121.

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 84267534670225 + 36944685429796 = 9179735^2 + 6078214^2 .

It is a cyclic number.

It is not a de Polignac number, because 121212220100021 - 2²² = 121212215905717 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 (121212220180021) 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, 536238500 + ... + 536464493.

It is an arithmetic number, because the mean of its divisors is an integer number (30303323229003).

Almost surely, 2^{121212220100021} is an apocalyptic number.

It is an amenable number.

121212220100021 is a deficient number, since it is larger than the sum of its proper divisors (1072815991).

121212220100021 is a wasteful number, since it uses less digits than its factorization.

121212220100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1072815990.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 121212220100021 its reverse (120001022212121), we get a palindrome (241213242312142).

The spelling of 121212220100021 in words is "one hundred twenty-one trillion, two hundred twelve billion, two hundred twenty million, one hundred thousand, twenty-one".