21212111121 has 8 divisors (see below), whose sum is σ = 28291318944. Its totient is φ = 14137155360.

The previous prime is 21212111101. The next prime is 21212111143. The reversal of 21212111121 is 12111121212.

It is a happy number.

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

It is not a de Polignac number, because 21212111121 - 2¹⁰ = 21212110097 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21212111121.

It is not an unprimeable number, because it can be changed into a prime (21212111101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1051356 + ... + 1071341.

It is an arithmetic number, because the mean of its divisors is an integer number (3536414868).

Almost surely, 2^21212111121 is an apocalyptic number.

It is an amenable number.

21212111121 is a deficient number, since it is larger than the sum of its proper divisors (7079207823).

21212111121 is a wasteful number, since it uses less digits than its factorization.

21212111121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2126031.

The product of its digits is 16, while the sum is 15.

Adding to 21212111121 its reverse (12111121212), we get a palindrome (33323232333).

It can be divided in two parts, 212 and 12111121, that multiplied together give a palindrome (2567557652).

The spelling of 21212111121 in words is "twenty-one billion, two hundred twelve million, one hundred eleven thousand, one hundred twenty-one".