21212122212101 has 8 divisors (see below), whose sum is σ = 21424307868408. Its totient is φ = 20999979000000.

The previous prime is 21212122212077. The next prime is 21212122212119. The reversal of 21212122212101 is 10121222121212.

It can be written as a sum of positive squares in 4 ways, for example, as 7196637849025 + 14015484363076 = 2682655^2 + 3743726^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212122212101 is a prime.

It is a super-2 number, since 2×21212122212101² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212122212301) 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 in 7 ways as a sum of consecutive naturals, for example, 9606050 + ... + 11606051.

It is an arithmetic number, because the mean of its divisors is an integer number (2678038483551).

Almost surely, 2^{21212122212101} is an apocalyptic number.

It is an amenable number.

21212122212101 is a deficient number, since it is larger than the sum of its proper divisors (212185656307).

21212122212101 is a wasteful number, since it uses less digits than its factorization.

21212122212101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21222103.

The product of its (nonzero) digits is 128, while the sum is 20.

Adding to 21212122212101 its reverse (10121222121212), we get a palindrome (31333344333313).

The spelling of 21212122212101 in words is "twenty-one trillion, two hundred twelve billion, one hundred twenty-two million, two hundred twelve thousand, one hundred one".