21210123231 has 12 divisors (see below), whose sum is σ = 33422012520. Its totient is φ = 12854620080.

The previous prime is 21210123227. The next prime is 21210123241. The reversal of 21210123231 is 13232101212.

It is not a de Polignac number, because 21210123231 - 2² = 21210123227 is a prime.

It is a super-2 number, since 2×21210123231² (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 (21210123241) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 107121736 + ... + 107121933.

It is an arithmetic number, because the mean of its divisors is an integer number (2785167710).

Almost surely, 2^21210123231 is an apocalyptic number.

21210123231 is a deficient number, since it is larger than the sum of its proper divisors (12211889289).

21210123231 is a wasteful number, since it uses less digits than its factorization.

21210123231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214243686 (or 214243683 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21210123231 its reverse (13232101212), we get a palindrome (34442224443).

It can be divided in two parts, 21210 and 123231, that added together give a palindrome (144441).

The spelling of 21210123231 in words is "twenty-one billion, two hundred ten million, one hundred twenty-three thousand, two hundred thirty-one".