121212221 has 8 divisors (see below), whose sum is σ = 131830104.
Its totient is φ = 110779200.
The previous prime is 121212209. The next prime is 121212253. The reversal of 121212221 is 122212121.
Adding to 121212221 its reverse (122212121), we get a palindrome (243424342).
It can be written as a sum of positive squares in 4 ways, for example, as 50836900 + 70375321 = 7130^2 + 8389^2
It is a sphenic number, since it is the product of 3 distinct primes.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-121212221 is a prime.
It is a Duffinian number.
It is a junction number, because it is equal to n+sod(n) for n = 121212196 and 121212205.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (121212281) by changing a digit.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44846 + ... + 47471.
It is an arithmetic number, because the mean of its divisors is an integer number (16478763).
Almost surely, 2121212221 is an apocalyptic number.
It is an amenable number.
121212221 is a deficient number, since it is larger than the sum of its proper divisors (10617883).
121212221 is a wasteful number, since it uses less digits than its factorization.
121212221 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 92431.
The product of its digits is 32, while the sum is 14.
The square root of 121212221 is about 11009.6421831048.
The cubic root of 121212221 is about 494.8977389681.
The spelling of 121212221 in words is "one hundred twenty-one million, two hundred twelve thousand, two hundred twenty-one".