21103111123 has 4 divisors (see below), whose sum is σ = 21830804640. Its totient is φ = 20375417608.

The previous prime is 21103111103. The next prime is 21103111129. The reversal of 21103111123 is 32111130112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21103111123 - 2¹³ = 21103102931 is a prime.

It is a super-2 number, since 2×21103111123² (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 = 21103111097 and 21103111106.

It is not an unprimeable number, because it can be changed into a prime (21103111129) 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 3 ways as a sum of consecutive naturals, for example, 363846715 + ... + 363846772.

It is an arithmetic number, because the mean of its divisors is an integer number (5457701160).

Almost surely, 2^21103111123 is an apocalyptic number.

21103111123 is a deficient number, since it is larger than the sum of its proper divisors (727693517).

21103111123 is an equidigital number, since it uses as much as digits as its factorization.

21103111123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 727693516.

The product of its (nonzero) digits is 36, while the sum is 16.

Adding to 21103111123 its reverse (32111130112), we get a palindrome (53214241235).

The spelling of 21103111123 in words is "twenty-one billion, one hundred three million, one hundred eleven thousand, one hundred twenty-three".