1221211212101 has 4 divisors (see below), whose sum is σ = 1293047165772. Its totient is φ = 1149375258432.

The previous prime is 1221211211959. The next prime is 1221211212187. The reversal of 1221211212101 is 1012121121221.

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 355615432225 + 865595779876 = 596335^2 + 930374^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221211212101 is a prime.

It is a super-2 number, since 2×1221211212101² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 71835953653 = 1221211212101 / (1 + 2 + 2 + 1 + 2 + 1 + 1 + 2 + 1 + 2 + 1 + 0 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221211212101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221211212701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35917976810 + ... + 35917976843.

It is an arithmetic number, because the mean of its divisors is an integer number (323261791443).

Almost surely, 2^{1221211212101} is an apocalyptic number.

It is an amenable number.

1221211212101 is a deficient number, since it is larger than the sum of its proper divisors (71835953671).

1221211212101 is an equidigital number, since it uses as much as digits as its factorization.

1221211212101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71835953670.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 1221211212101 its reverse (1012121121221), we get a palindrome (2233332333322).

The spelling of 1221211212101 in words is "one trillion, two hundred twenty-one billion, two hundred eleven million, two hundred twelve thousand, one hundred one".