21123110013 has 4 divisors (see below), whose sum is σ = 28164146688. Its totient is φ = 14082073340.

The previous prime is 21123109999. The next prime is 21123110023. The reversal of 21123110013 is 31001132112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21123110013 - 2²⁸ = 20854674557 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21123109974 and 21123110001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123110023) 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 3 ways as a sum of consecutive naturals, for example, 3520518333 + ... + 3520518338.

It is an arithmetic number, because the mean of its divisors is an integer number (7041036672).

Almost surely, 2^21123110013 is an apocalyptic number.

It is an amenable number.

21123110013 is a deficient number, since it is larger than the sum of its proper divisors (7041036675).

21123110013 is an equidigital number, since it uses as much as digits as its factorization.

21123110013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7041036674.

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

Adding to 21123110013 its reverse (31001132112), we get a palindrome (52124242125).

The spelling of 21123110013 in words is "twenty-one billion, one hundred twenty-three million, one hundred ten thousand, thirteen".