21212012231 has 2 divisors, whose sum is σ = 21212012232. Its totient is φ = 21212012230.

The previous prime is 21212012219. The next prime is 21212012249. The reversal of 21212012231 is 13221021212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212012231 is a prime.

It is a super-2 number, since 2×21212012231² (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 (21212012251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606006115 + 10606006116.

It is an arithmetic number, because the mean of its divisors is an integer number (10606006116).

Almost surely, 2^21212012231 is an apocalyptic number.

21212012231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212012231 is an equidigital number, since it uses as much as digits as its factorization.

21212012231 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21212012231 its reverse (13221021212), we get a palindrome (34433033443).

The spelling of 21212012231 in words is "twenty-one billion, two hundred twelve million, twelve thousand, two hundred thirty-one".