21211312231 has 4 divisors (see below), whose sum is σ = 21255595200. Its totient is φ = 21167029264.

The previous prime is 21211312189. The next prime is 21211312259. The reversal of 21211312231 is 13221311212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21211312231 - 2³¹ = 19063828583 is a prime.

It is a super-2 number, since 2×21211312231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211312199 and 21211312208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211312261) 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 3 ways as a sum of consecutive naturals, for example, 22140766 + ... + 22141723.

It is an arithmetic number, because the mean of its divisors is an integer number (5313898800).

Almost surely, 2^21211312231 is an apocalyptic number.

21211312231 is a deficient number, since it is larger than the sum of its proper divisors (44282969).

21211312231 is an equidigital number, since it uses as much as digits as its factorization.

21211312231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44282968.

The product of its digits is 144, while the sum is 19.

Adding to 21211312231 its reverse (13221311212), we get a palindrome (34432623443).

The spelling of 21211312231 in words is "twenty-one billion, two hundred eleven million, three hundred twelve thousand, two hundred thirty-one".