21011100217 has 2 divisors, whose sum is σ = 21011100218. Its totient is φ = 21011100216.

The previous prime is 21011100211. The next prime is 21011100221. The reversal of 21011100217 is 71200111012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19630531881 + 1380568336 = 140109^2 + 37156^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21011100217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21011100217.

It is not a weakly prime, because it can be changed into another prime (21011100211) 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 as a sum of consecutive naturals, namely, 10505550108 + 10505550109.

It is an arithmetic number, because the mean of its divisors is an integer number (10505550109).

Almost surely, 2^21011100217 is an apocalyptic number.

It is an amenable number.

21011100217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011100217 is an equidigital number, since it uses as much as digits as its factorization.

21011100217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28, while the sum is 16.

Adding to 21011100217 its reverse (71200111012), we get a palindrome (92211211229).

The spelling of 21011100217 in words is "twenty-one billion, eleven million, one hundred thousand, two hundred seventeen".