21221201212117 has 2 divisors, whose sum is σ = 21221201212118. Its totient is φ = 21221201212116.

The previous prime is 21221201212109. The next prime is 21221201212151. The reversal of 21221201212117 is 71121210212212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12286924783441 + 8934276428676 = 3505271^2 + 2989026^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221201212117 - 2³ = 21221201212109 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21221201212091 and 21221201212100.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221201212157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610600606058 + 10610600606059.

It is an arithmetic number, because the mean of its divisors is an integer number (10610600606059).

Almost surely, 2^{21221201212117} is an apocalyptic number.

It is an amenable number.

21221201212117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221201212117 is an equidigital number, since it uses as much as digits as its factorization.

21221201212117 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 25.

Adding to 21221201212117 its reverse (71121210212212), we get a palindrome (92342411424329).

The spelling of 21221201212117 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred one million, two hundred twelve thousand, one hundred seventeen".