211221110021 has 2 divisors, whose sum is σ = 211221110022. Its totient is φ = 211221110020.

The previous prime is 211221110017. The next prime is 211221110059. The reversal of 211221110021 is 120011122112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 210326800996 + 894309025 = 458614^2 + 29905^2 .

It is a cyclic number.

It is not a de Polignac number, because 211221110021 - 2² = 211221110017 is a prime.

It is a super-2 number, since 2×211221110021² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 211221109978 and 211221110005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211221110071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105610555010 + 105610555011.

It is an arithmetic number, because the mean of its divisors is an integer number (105610555011).

Almost surely, 2^211221110021 is an apocalyptic number.

It is an amenable number.

211221110021 is a deficient number, since it is larger than the sum of its proper divisors (1).

211221110021 is an equidigital number, since it uses as much as digits as its factorization.

211221110021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 211221110021 its reverse (120011122112), we get a palindrome (331232232133).

The spelling of 211221110021 in words is "two hundred eleven billion, two hundred twenty-one million, one hundred ten thousand, twenty-one".