21111030123 has 4 divisors (see below), whose sum is σ = 28148040168. Its totient is φ = 14074020080.

The previous prime is 21111030113. The next prime is 21111030139. The reversal of 21111030123 is 32103011112.

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 21111030123 - 2⁴ = 21111030107 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21111030113) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3518505018 + ... + 3518505023.

It is an arithmetic number, because the mean of its divisors is an integer number (7037010042).

Almost surely, 2^21111030123 is an apocalyptic number.

21111030123 is a deficient number, since it is larger than the sum of its proper divisors (7037010045).

21111030123 is an equidigital number, since it uses as much as digits as its factorization.

21111030123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7037010044.

The product of its (nonzero) digits is 36, while the sum is 15.

Adding to 21111030123 its reverse (32103011112), we get a palindrome (53214041235).

The spelling of 21111030123 in words is "twenty-one billion, one hundred eleven million, thirty thousand, one hundred twenty-three".