13111111021 has 4 divisors (see below), whose sum is σ = 13246277212. Its totient is φ = 12975944832.

The previous prime is 13111111007. The next prime is 13111111051. The reversal of 13111111021 is 12011111131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12011111131 = 461 ⋅26054471.

It can be written as a sum of positive squares in 2 ways, for example, as 10218177225 + 2892933796 = 101085^2 + 53786^2 .

It is a cyclic number.

It is not a de Polignac number, because 13111111021 - 2⁵ = 13111110989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13111110992 and 13111111010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13111111051) 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, 67582950 + ... + 67583143.

It is an arithmetic number, because the mean of its divisors is an integer number (3311569303).

Almost surely, 2^13111111021 is an apocalyptic number.

It is an amenable number.

13111111021 is a deficient number, since it is larger than the sum of its proper divisors (135166191).

13111111021 is an equidigital number, since it uses as much as digits as its factorization.

13111111021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135166190.

The product of its (nonzero) digits is 6, while the sum is 13.

Adding to 13111111021 its reverse (12011111131), we get a palindrome (25122222152).

It can be divided in two parts, 131111110 and 21, that added together give a palindrome (131111131).

The spelling of 13111111021 in words is "thirteen billion, one hundred eleven million, one hundred eleven thousand, twenty-one".