21122111212123 has 4 divisors (see below), whose sum is σ = 21850459874640. Its totient is φ = 20393762549608.

The previous prime is 21122111212043. The next prime is 21122111212201. The reversal of 21122111212123 is 32121211122112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21122111212123 is a prime.

It is a super-2 number, since 2×21122111212123² (a number of 27 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 = 21122111212094 and 21122111212103.

It is not an unprimeable number, because it can be changed into a prime (21122111213123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 364174331215 + ... + 364174331272.

It is an arithmetic number, because the mean of its divisors is an integer number (5462614968660).

Almost surely, 2^{21122111212123} is an apocalyptic number.

21122111212123 is a deficient number, since it is larger than the sum of its proper divisors (728348662517).

21122111212123 is an equidigital number, since it uses as much as digits as its factorization.

21122111212123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 728348662516.

The product of its digits is 192, while the sum is 22.

Adding to 21122111212123 its reverse (32121211122112), we get a palindrome (53243322334235).

The spelling of 21122111212123 in words is "twenty-one trillion, one hundred twenty-two billion, one hundred eleven million, two hundred twelve thousand, one hundred twenty-three".