21221211231 has 144 divisors (see below), whose sum is σ = 37286645760. Its totient is φ = 11568268800.

The previous prime is 21221211227. The next prime is 21221211247. The reversal of 21221211231 is 13211212212.

21221211231 is a `hidden beast` number, since 2 + 1 + 221 + 211 + 231 = 666.

It is not a de Polignac number, because 21221211231 - 2² = 21221211227 is a prime.

It is a super-2 number, since 2×21221211231² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221211331) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 59111830 + ... + 59112188.

It is an arithmetic number, because the mean of its divisors is an integer number (258935040).

Almost surely, 2^21221211231 is an apocalyptic number.

21221211231 is a deficient number, since it is larger than the sum of its proper divisors (16065434529).

21221211231 is a wasteful number, since it uses less digits than its factorization.

21221211231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 538 (or 524 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

Adding to 21221211231 its reverse (13211212212), we get a palindrome (34432423443).

The spelling of 21221211231 in words is "twenty-one billion, two hundred twenty-one million, two hundred eleven thousand, two hundred thirty-one".