21102121217 has 2 divisors, whose sum is σ = 21102121218. Its totient is φ = 21102121216.

The previous prime is 21102121153. The next prime is 21102121223. The reversal of 21102121217 is 71212120112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19351870321 + 1750250896 = 139111^2 + 41836^2 .

It is a cyclic number.

It is not a de Polignac number, because 21102121217 - 2⁶ = 21102121153 is a prime.

It is a super-3 number, since 3×21102121217³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (21102126217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551060608 + 10551060609.

It is an arithmetic number, because the mean of its divisors is an integer number (10551060609).

Almost surely, 2^21102121217 is an apocalyptic number.

It is an amenable number.

21102121217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21102121217 is an equidigital number, since it uses as much as digits as its factorization.

21102121217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 112, while the sum is 20.

Adding to 21102121217 its reverse (71212120112), we get a palindrome (92314241329).

The spelling of 21102121217 in words is "twenty-one billion, one hundred two million, one hundred twenty-one thousand, two hundred seventeen".