21212112101 has 2 divisors, whose sum is σ = 21212112102. Its totient is φ = 21212112100.

The previous prime is 21212112079. The next prime is 21212112109. The reversal of 21212112101 is 10121121212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21199651201 + 12460900 = 145601^2 + 3530^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212112101 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21212112109) 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, 10606056050 + 10606056051.

It is an arithmetic number, because the mean of its divisors is an integer number (10606056051).

Almost surely, 2^21212112101 is an apocalyptic number.

It is an amenable number.

21212112101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212112101 is an equidigital number, since it uses as much as digits as its factorization.

21212112101 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 21212112101 its reverse (10121121212), we get a palindrome (31333233313).

The spelling of 21212112101 in words is "twenty-one billion, two hundred twelve million, one hundred twelve thousand, one hundred one".