21121111121 has 8 divisors (see below), whose sum is σ = 23531451264. Its totient is φ = 18792477520.

The previous prime is 21121111087. The next prime is 21121111127. The reversal of 21121111121 is 12111112112.

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

It is a cyclic number.

It is not a de Polignac number, because 21121111121 - 2⁶ = 21121111057 is a prime.

It is a super-2 number, since 2×21121111121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21121111096 and 21121111105.

It is not an unprimeable number, because it can be changed into a prime (21121111127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20426090 + ... + 20427123.

It is an arithmetic number, because the mean of its divisors is an integer number (2941431408).

Almost surely, 2^21121111121 is an apocalyptic number.

It is an amenable number.

21121111121 is a deficient number, since it is larger than the sum of its proper divisors (2410340143).

21121111121 is a wasteful number, since it uses less digits than its factorization.

21121111121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40853271.

The product of its digits is 8, while the sum is 14.

Adding to 21121111121 its reverse (12111112112), we get a palindrome (33232223233).

Subtracting from 21121111121 its reverse (12111112112), we obtain a palindrome (9009999009).

The spelling of 21121111121 in words is "twenty-one billion, one hundred twenty-one million, one hundred eleven thousand, one hundred twenty-one".