1212121 has 2 divisors, whose sum is σ = 1212122.
Its totient is φ = 1212120.
The previous prime is 1212119. The next prime is 1212149.
1212121 is nontrivially palindromic in base 10.
1212121 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 921600 + 290521 = 960^2 + 539^2
It is a palprime.
It is a cyclic number.
It is not a de Polignac number, because 1212121 - 21 = 1212119 is a prime.
Together with 1212119, it forms a pair of twin primes.
It is an alternating number because its digits alternate between odd and even.
1212121 is an undulating number in base 10.
It is a junction number, because it is equal to n+sod(n) for n = 1212098 and 1212107.
It is not a weakly prime, because it can be changed into another prime (1212191) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (13) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606060 + 606061.
It is an arithmetic number, because the mean of its divisors is an integer number (606061).
21212121 is an apocalyptic number.
It is an amenable number.
1212121 is a deficient number, since it is larger than the sum of its proper divisors (1).
1212121 is an equidigital number, since it uses as much as digits as its factorization.
1212121 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 8, while the sum is 10.
The square root of 1212121 is about 1100.9636687920.
The cubic root of 1212121 is about 106.6224502065.
It can be divided in two parts, 12121 and 21, that multiplied together give a triangular number (254541 = T713).
The spelling of 1212121 in words is "one million, two hundred twelve thousand, one hundred twenty-one".