21112123013 has 4 divisors (see below), whose sum is σ = 22354012620. Its totient is φ = 19870233408.

The previous prime is 21112123007. The next prime is 21112123051. The reversal of 21112123013 is 31032121112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10514861764 + 10597261249 = 102542^2 + 102943^2 .

It is a cyclic number.

It is not a de Polignac number, because 21112123013 - 2⁶ = 21112122949 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1241889589 = 21112123013 / (2 + 1 + 1 + 1 + 2 + 1 + 2 + 3 + 0 + 1 + 3).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21112122982 and 21112123000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112123063) 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, 620944778 + ... + 620944811.

It is an arithmetic number, because the mean of its divisors is an integer number (5588503155).

Almost surely, 2^21112123013 is an apocalyptic number.

It is an amenable number.

21112123013 is a deficient number, since it is larger than the sum of its proper divisors (1241889607).

21112123013 is a wasteful number, since it uses less digits than its factorization.

21112123013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1241889606.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 21112123013 its reverse (31032121112), we get a palindrome (52144244125).

The spelling of 21112123013 in words is "twenty-one billion, one hundred twelve million, one hundred twenty-three thousand, thirteen".