21131221131 has 6 divisors (see below), whose sum is σ = 30522874980. Its totient is φ = 14087480748.

The previous prime is 21131221129. The next prime is 21131221157. The reversal of 21131221131 is 13112213112.

It is not a de Polignac number, because 21131221131 - 2¹ = 21131221129 is a prime.

It is a super-2 number, since 2×21131221131² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21131226131) 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 5 ways as a sum of consecutive naturals, for example, 1173956721 + ... + 1173956738.

It is an arithmetic number, because the mean of its divisors is an integer number (5087145830).

Almost surely, 2^21131221131 is an apocalyptic number.

21131221131 is a deficient number, since it is larger than the sum of its proper divisors (9391653849).

21131221131 is a wasteful number, since it uses less digits than its factorization.

21131221131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2347913465 (or 2347913462 counting only the distinct ones).

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

Adding to 21131221131 its reverse (13112213112), we get a palindrome (34243434243).

The spelling of 21131221131 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty-one thousand, one hundred thirty-one".