21111212212101 has 48 divisors (see below), whose sum is σ = 33744640056192. Its totient is φ = 12610877299200.

The previous prime is 21111212211983. The next prime is 21111212212127. The reversal of 21111212212101 is 10121221211112.

It is a happy number.

21111212212101 is a `hidden beast` number, since 2 + 111 + 121 + 221 + 210 + 1 = 666.

It is not a de Polignac number, because 21111212212101 - 2⁹ = 21111212211589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111212212141) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9716976 + ... + 11689398.

It is an arithmetic number, because the mean of its divisors is an integer number (703013334504).

Almost surely, 2^{21111212212101} is an apocalyptic number.

It is an amenable number.

21111212212101 is a deficient number, since it is larger than the sum of its proper divisors (12633427844091).

21111212212101 is a wasteful number, since it uses less digits than its factorization.

21111212212101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1973994 (or 1973991 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 18.

Adding to 21111212212101 its reverse (10121221211112), we get a palindrome (31232433423213).

The spelling of 21111212212101 in words is "twenty-one trillion, one hundred eleven billion, two hundred twelve million, two hundred twelve thousand, one hundred one".