21021212231 has 2 divisors, whose sum is σ = 21021212232. Its totient is φ = 21021212230.

The previous prime is 21021212221. The next prime is 21021212237. The reversal of 21021212231 is 13221212012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21021212231 - 2¹⁸ = 21020950087 is a prime.

It is a super-2 number, since 2×21021212231² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021212237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510606115 + 10510606116.

It is an arithmetic number, because the mean of its divisors is an integer number (10510606116).

Almost surely, 2^21021212231 is an apocalyptic number.

21021212231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021212231 is an equidigital number, since it uses as much as digits as its factorization.

21021212231 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21021212231 its reverse (13221212012), we get a palindrome (34242424243).

The spelling of 21021212231 in words is "twenty-one billion, twenty-one million, two hundred twelve thousand, two hundred thirty-one".