21311212133 has 2 divisors, whose sum is σ = 21311212134. Its totient is φ = 21311212132.

The previous prime is 21311212127. The next prime is 21311212163. The reversal of 21311212133 is 33121211312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19145426689 + 2165785444 = 138367^2 + 46538^2 .

It is a cyclic number.

It is not a de Polignac number, because 21311212133 - 2¹⁰ = 21311211109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21311212163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655606066 + 10655606067.

It is an arithmetic number, because the mean of its divisors is an integer number (10655606067).

Almost surely, 2^21311212133 is an apocalyptic number.

It is an amenable number.

21311212133 is a deficient number, since it is larger than the sum of its proper divisors (1).

21311212133 is an equidigital number, since it uses as much as digits as its factorization.

21311212133 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216, while the sum is 20.

Adding to 21311212133 its reverse (33121211312), we get a palindrome (54432423445).

The spelling of 21311212133 in words is "twenty-one billion, three hundred eleven million, two hundred twelve thousand, one hundred thirty-three".