13123111221 has 24 divisors (see below), whose sum is σ = 20829803904. Its totient is φ = 7895338560.

The previous prime is 13123111217. The next prime is 13123111229. The reversal of 13123111221 is 12211132131.

13123111221 is a `hidden beast` number, since 131 + 2 + 311 + 1 + 221 = 666.

It is not a de Polignac number, because 13123111221 - 2² = 13123111217 is a prime.

It is a super-2 number, since 2×13123111221² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 13123111194 and 13123111203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13123111229) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 470221 + ... + 497346.

It is an arithmetic number, because the mean of its divisors is an integer number (867908496).

Almost surely, 2^13123111221 is an apocalyptic number.

13123111221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

13123111221 is a deficient number, since it is larger than the sum of its proper divisors (7706692683).

13123111221 is a wasteful number, since it uses less digits than its factorization.

13123111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 967721 (or 967718 counting only the distinct ones).

The product of its digits is 72, while the sum is 18.

Adding to 13123111221 its reverse (12211132131), we get a palindrome (25334243352).

The spelling of 13123111221 in words is "thirteen billion, one hundred twenty-three million, one hundred eleven thousand, two hundred twenty-one".