213123131221 has 16 divisors (see below), whose sum is σ = 286151338368. Its totient is φ = 153295358400.

The previous prime is 213123131171. The next prime is 213123131279. The reversal of 213123131221 is 122131321312.

It is a cyclic number.

It is not a de Polignac number, because 213123131221 - 2¹⁷ = 213123000149 is a prime.

It is a super-2 number, since 2×213123131221² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 213123131192 and 213123131201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213123131281) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 106454110 + ... + 106456111.

It is an arithmetic number, because the mean of its divisors is an integer number (17884458648).

Almost surely, 2^213123131221 is an apocalyptic number.

It is an amenable number.

213123131221 is a deficient number, since it is larger than the sum of its proper divisors (73028207147).

213123131221 is a wasteful number, since it uses less digits than its factorization.

213123131221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212910252.

The product of its digits is 432, while the sum is 22.

Adding to 213123131221 its reverse (122131321312), we get a palindrome (335254452533).

The spelling of 213123131221 in words is "two hundred thirteen billion, one hundred twenty-three million, one hundred thirty-one thousand, two hundred twenty-one".