21101212111121 has 8 divisors (see below), whose sum is σ = 21245282721000. Its totient is φ = 20957174191360.

The previous prime is 21101212111081. The next prime is 21101212111153. The reversal of 21101212111121 is 12111121210112.

It can be written as a sum of positive squares in 4 ways, for example, as 5023806718225 + 16077405392896 = 2241385^2 + 4009664^2 .

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-21101212111121 is a prime.

It is a super-2 number, since 2×21101212111121² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21101212111121.

It is not an unprimeable number, because it can be changed into a prime (21101212411121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6876440 + ... + 9459801.

It is an arithmetic number, because the mean of its divisors is an integer number (2655660340125).

Almost surely, 2^{21101212111121} is an apocalyptic number.

It is an amenable number.

21101212111121 is a deficient number, since it is larger than the sum of its proper divisors (144070609879).

21101212111121 is a wasteful number, since it uses less digits than its factorization.

21101212111121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16345059.

The product of its (nonzero) digits is 16, while the sum is 17.

Adding to 21101212111121 its reverse (12111121210112), we get a palindrome (33212333321233).

The spelling of 21101212111121 in words is "twenty-one trillion, one hundred one billion, two hundred twelve million, one hundred eleven thousand, one hundred twenty-one".