21211212021121 has 12 divisors (see below), whose sum is σ = 22332598291120. Its totient is φ = 20090327420520.

The previous prime is 21211212021119. The next prime is 21211212021161. The reversal of 21211212021121 is 12112021211212.

It is a happy number.

It is not a de Polignac number, because 21211212021121 - 2¹ = 21211212021119 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21211212021161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 464208886 + ... + 464254576.

Almost surely, 2^{21211212021121} is an apocalyptic number.

It is an amenable number.

21211212021121 is a deficient number, since it is larger than the sum of its proper divisors (1121386269999).

21211212021121 is an frugal number, since it uses more digits than its factorization.

21211212021121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55596 (or 50653 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21211212021121 its reverse (12112021211212), we get a palindrome (33323233232333).

The spelling of 21211212021121 in words is "twenty-one trillion, two hundred eleven billion, two hundred twelve million, twenty-one thousand, one hundred twenty-one".